Of course, sometimes they aren't. The Timey-Wimey Ball is the result of a series or movie where the writers are a wee bit confused or forgetful about exactly which kind of time travel can happen, sometimes within the span of one episode! One day You Can't Fight Fate (or at least not without the Butterfly of Doom coming along), but the next you can Screw Destiny and Set Right What Once Went Wrong by killing Hitler and changing the past for the better. Especially headachy because there's no Temporal Paradox, or if there is it's totally arbitrary.

The standard Hand Wave (if one is given) is that time is very complicated and the particulars of the situation affect how the rules apply in ways that a layperson wouldn't understand. Which is one of the many reasons why some fiction fans really, really HATE time travel.

Then there is Princess Hisui's plan to use the Eclipse Gate to kill Zeref and avert all the suffering he causes in the future. Later chapters reveal that it would have caused a Temporal Paradox, as Zeref was the one to conceive the idea of the Eclipse Gate.

Haruhi Suzumiya. The first thing we hear about time travel is that it's like a picture book; it looks continuous, but it's not, and scribbling on one page won't change the ending, so it's impossible to change the future. That gets thrown out the window pretty quick, with time loops up the wazoo. Several space-time locations get multiple time loops overlapping over them at the same time. However, starting in Novel 9, the timeline splits— not diverges, splits— and later fuses back together, and in novel 10 it is revealed that the evil time traveler Fujiwara is from a different future than Mikuru. In his, she's dead—and he wants to fix that, because she's his big sister. Unfortunately, in the timeline she's from (where she survived), her little brother never existed in the first place. So it's possible to change the future, right? Maybe. Because when all this craziness is going on, Kyon brings up the picture book analogy again, and it's confirmed that that is how time travel works (though at the same time it's implied to be an incomplete explanation). The mechanics of time travel in The 'Verse are pretty much incoherent now.

Mahou no Iroha: Time travel is apparently very possible with the help of magic, and the Magical Girl main character somehow changes some things but not others that leaves readers scratching their head.

There's a Back to the Future card game based on the film, where again each player is someone from an alternate timeline trying to manipulate the universe into one where they exist. However, one big difference is that after doing so, the time travelers have to stop Emmett Brown from inventing time travel so that nobody else can mess with it and their timeline becomes the only timeline. Paradox much?

In Chrononauts, players are competing time travelers from alternate futures sent on missions into the past to recover various historical artifacts. Each player is playing tug-of-war with the timeline so that they can return home, which results in a very fluid history. If enough paradoxes pile up, they can even destroy the universe.

In US Patent #1 by Cheapass Games, each player has invented a time machine and hopes to profit from it, but the only one who will be able to profit is the one who holds a patent. Given that patents can be invalidated by proof of earlier work, the only patent that matters for a time machine is the chronologically first one. So the entire game consists of a race through time to be the first in line on the first day the Patent Office opens.

Comic Books

Marvel Comics' Adam Warlock, specifically his evil future self The Magus embodies this trope. Adam Warlock met his futureself and immediately The Magus set about trying to ensure Adam would turn into him. This did not work when "Thanos" and the In-Betweener interfered and Adam was given a choice of timelines, wherein he chose the shortest. The Magus appeared again when Adam Warlock attained the Infinity Gauntlet and divested himself of his good self (The Goddess) and his evil self (The Magus). The Magus initiated the Infinity War, but was defeated. Later, to seal the Fault in space caused, in part by the Annihilation Wave, The Phalanx Invasion, and the War of Kings, Adam Warlock who, as he expanded magical energy slowly started turning into The Magus, used an "unused" timeline to repair the fault. That particular "unused" timeline was the one in which he became The Magus.

Say the word "Kang" to a fan and they'll often shudder. His time-travel schemes are so complex that his future self, Immortus, is another major Avengers enemy, and the two can often be seen fighting each other. To give a sense of scale: most Marvel Handbook profiles are one to three pages long except for major characters like Spider-Man, Iron Man or Wolverine. Kang's gets six pages, and the bottom half of each page is devoted to Kang's timeline, which is chronological in years but requires jumping around from page to page to get Kang's chronological story.

Made even more confusing with the addition of a third iteration of Kang in Young Avengers: Iron Lad who actually kills Kang in an attempt to prevent himself from becoming Kang and ultimately realizes the only way to save the future is to become Kang anyway. If you find yourself confused, know at least that you aren't alone:

Jessica Jones: Is this a time-travel thing? Because I hate time-travel things. Iron Man: If it's Kang, it's a time-travel thing. Jessica: See, this is why I hate Kang...

You can also thank Kang for raising one of the X-Men's greatest foes, Apocalypse.

The DCU has all sorts of fun here, especially when Booster Gold is involved, but it's been proven time and again that trying to Screw Destiny usually ends badly. Aside from that, the Timey-Wimey Ball hurts Booster's head as much as it hurts the audience's.

Professor Zoom has (retroactively) had his hands on the Timey-Wimey Ball from day one. In a single issue you see him edit his brother, parents, scholarly rival, and lover out of his own history, apparently to make sure he'll actually become the supervillain he is. It Makes Sense in Context.

The Flash himself historically averted this trope when at all possible. Barry and Wally repeatedly refused to even try holding the Timey-Wimey Ball. Until Flashpoint. Nice Job Breaking It, Hero!.

The second Zoom came into being because he tried to grab the Timey-Wimey Ball and blew himself up. Unfortunately for him, his powers (unlike every other speedster) avert the trope.

An issue of Impulse had a Mad Scientist invent a time machine, and attempt to change the past so that he would rule the world. Impulse and Max Mercury go back in time to stop him, but wind up stuck in the far distant past. Max lectures Bart on the Butterfly of Doom, and how even eating a fish might cause irreparable harm to the future. But then they discover that the mad scientist is now trapped in the past as well. The three of them decide that the best way to get home is to cause as much damage and destruction as possible. Their logic is that if they completely change the past, it will alter the future so much that the scientist will never exist, which means he will never invent his time machine, which means they won't have travelled to the past in the first place, which means they won't actually cause any damage at all and find themselves back home. Confused?

Gold Digger: With all the dimension-hopping, time-traveling technology in Gold Digger, naturally there's a lot of Timey-Wimey Ball action going on. However, of special note is issue #50 of the color series, which features an artifact that is an actual ball of string that can warp time and space.

Iznogoud: In Iznogoud's Childhood, Iznogoud experiments a type of time travel in which the present and the past happen at the same time for a while, which he tries to exploit by attempting to get rid of the Caliph's younger self. The whole thing eventually end up being a Stable Time Loop, in which Iznogoud's time travel is what causes his younger self (who Used to Be a Sweet Kid) to transform into the Jerk Ass we're familiar with. However, earlier in the comic, Iznogoud stabs younger Wa'at Alahf to test the time travelling nature, and that case works on a Ripple Effect basis, in which adult Wa'at Alahf shows up with a scar he'd never had.

Limbo in the Marvel Universe (mainly shows up in association with X-Men) is an entire dimension of timey-wimeyness. When the X-Men entered and got separated, both Wolverine and Colossus encountered long-dead versions of each other, and managed to escape just fine in the end. Storm was stopped at one point by her older self, who had remained in Limbo for decades studying magic. And Nightcrawler killed his older self.

Sonic the Hedgehog has an interesting variation at one point. Knuckles, juiced up on Chaos Energy, was given the chance to bring back everyone on the Floating Island through his power. To do so, he keeps bouncing back in time and stopping a certain event. Not only does that have bad consequences for him, but what he doesn't know is that he keeps futzing up the actual Sonic events, creating timelines such as a pure SatAM world, one based off of the 1995 OVA and a timeline where Robotnik never initiated his coup. At the end, Knuckles decides to stop that and just bring everyone back from the prison the Dark Legion launched them into.

In the 1980s Marvel The Transformers comic, one can alter the past to suit the present. However, there is also the possibility that one travels to a different universe that is simply the same as your own. So thus, any attempt to travel back in time to, say, build a giant cannon to destroy the dark god who created you when he turns his attention to Earth in order to free yourself from his control as Galvatron tried to, can potentially end in failure as it is not your own universe. As it turned out, it WAS Galvatron's own universe.

John Byrne's run on Wonder Woman has a classic example of the rules changing within a story. When Diana's mother becomes the new Wonder Woman, Jay Garrick recognises her as the mysterious woman who was involved in one of his adventures in The Golden Age of Comic Books, and who he never really met. When he tells Hippolyta this, she travels to the past in order to maintain the timeline by ensuring everything happens the way Jay remembers. Once she gets there, however, she decides to stick around and become the Golden Age Wonder Woman and a member of the Justice Society of America. History is therefore completely altered after all, but no-one seems to mind.

Zipi y Zape: All the story about the time-travel machine built in a barrel revolves around this trope. In the first chapter, the twins use it to transform a wall lizard into its evolutionary ancestor (which turns out to be a crocodile). In all the other chapters, the twins use it themselves; it no longer makes anything appear in the present time, but depending on the chapter, it either just takes them to the past, or somehow transforms them in their ancestor (and, somehow, with all the knowledge and remembrances that those ancestors have). In one chapter, when their mother makes an omelette with an egg found in the past, the twins remark that its strange look is due to the fact that the egg had over two hundred years, even though the time travel should have prevented the egg from aging. Finally, in the last chapter, the twins get trapped in the future when their machine gets broken; strangely, in a rare example of an invertedSan Dimas Time, it's said that house prices were getting higher because of the twins' absence.

Teen Titans Go!: In Issue #31, a villain changes Robin's past to become his mentor and the other titans are helped by Good!Robin's future self a.k.a. Nightwing. During the epilogue, Beast Boy wonders how that Nightwing could exist at the same time as Bad!Robin and Raven handwaves it by saying they don't fully understand how Time Travel works.

All-New X-Men had a hard time deciding whether they were changing the timeline, creating a new one, creating several new ones, or just messing everything up – OR whether it had all already happened. Both this book and the tie-in Children of the Atom had the added conundrum that while people from the past who were still alive in the present (and one who was dead in the present) were visiting the present, so were a bunch of people from the future, at least one of whom was presently visiting from the past. Several times.

Fan Works

Discussed at length in The Parselmouth Of Gryffindor: time-travel magic only exists thanks to a loophole in the rules of the universe, and so while theoretically it ought to allow you to change the past, in practice, magic does its best to manipulate probablity so that the result is a Stable Time Loop. The farther back in time you go and the more efforts you make to change the past, the more unstable space-time becomes until you're either obliterated or kicked back to your home time period.

In the Doctor Who fanfic Gemini, this trope is invoked so as to defyStable Time Loop: It’s easier for the Daleks to change the past than it is for anybody else, so the military is trying to create super-soldiers that can change the timeline as easily as the Daleks can.

This is actually an inversion, or something. The writer doesn't appear to be confused about what kind of time travel is possible; rather, he works very hard to make sure that it follows consistent rules. And the characters know about these rules. But trying to work out the logical implications of these rules results in confused characters and confused readers.

In the Mass Effect's Crucible, the multiverses work mainly as "Overwriting the timeline" but later the CrucibleVerse itself become a hybrid version of both "Overwritting" and "Branching timelines". Basically, time can be seen as a river with different universes as balls floating in it. Each ball has in front of it what look like millions of almost identical versions of itself in different points spread across the width of the river while behind there's nothing. As the ball floats forward depending on how the river flows ­it'll take the place of one of the many copies and the others in line with it disappear. The potential what ­might have ­been's all disappear when the ball finally arrives. So as the future hybrids come to the present of the CrucibleVerse and change it, the Bad Future soon disappear to be replaced by a new future.

But due to Sam, Aunties and their "employers"'s intervention, a new future, different CrucibleVerse is created by pulling the bad future backwards and, as it can't survive on its own, branching off from the main timeline like a Siamese twin. In new time line, the souls of those time travellers from the Bad Future are put into their younger bodies while alt.Jane meet her main counterpart to know everything that happened in the now disappeared bad future to change the new twin universe for the better. This also cause Life and Death from the main timeline to work double-duty since they partly exist outside of time and space.

In My Immortal, the main character Ebony travels back in time to teach a young Voldemort about love. But when she does, the plot really starts to get strange. A few examples are that characters in the past know what will happen in the present, that items will not work in time-periods where its not invented yet and that people can't die outside their native time-period.

Similarly, Time v3.0, being a Doctor Who fanfic that does its best to encompass all the chaotic mess that was the Time War, uses this trope up, down, and sideways.

A Crown of Stars tries to avert this. Daniel and Rayana explain Shinji and Asuka that they technically can stop Second Impact and other tragedies... but then Shinji and Asuka would be completely different people, ergo their fixes would be meaningless. So both gods use time-travel to undo the consequences of those tragedies.

In Once More with Feeling Shinji remembers everything what happened in the original timeline, even though a lot of events are significantly different due to his actions.

In The Second Try, Shinji and Asuka set to avert Third Impact, even though it'd mean that their beloved daughter will never be born. In order to avoid this, Kaworu sends Aki back in time, but she arrives several months later than her parents.

Thousand Shinji: The Warhammer 40,000 gods changed the past so they never existed. Even so, Chaos Marine Khenmu and his brothers-in-arms keep existing, and the fragments of the gods still existed and remembered the original timeline.

"Brother on Brother, Daughter on Mother" attempts to make some sense out of the trope as it applies to Star Trek (with the obligatory Shout-Out to the Trope Namer) with a variant of the many worlds theory wherein time is actually a rope made of strands of probabilistic outcomes that can tangle up. The purpose of the Time Police is to prevent that rope from "fraying" due to major temporal incursions; smaller incidents are usually papered over by the inertia of time itself.

Films — Live-Action

The time travel in About Time appears to have at least two different modes, but the explanation is very scanty. Tim can go back to a previous occasion and change what he did, but then he can choose to either live from that point onwards, or snap forward to where he jumped from and see what the changes have been. The event described in Secret Keeper seems to suggest he can also undo these changes.

Although, ironically, the conversation that confuses Austin doesn't actually contain any inherent paradoxes; the Doctor Evil he was chasing was the contemporary version who had also gone back in time. Past Doctor Evil and Past Austin were both frozen cryogenically during the time period in question so there would be no crossover.

Back to the Future has different things happening to the hero as the past is changed. Read the timeline for the trilogy at this page if you have any questions about how it works. There isn't a single concern here that isn't covered there one way or another. To summarize, you can create alternate timelines, and any time it seemsYou Already Changed the Past (like Chuck Berry hearing the song he would later write) it's really just causing the same event in a different way (in the original timeline Chuck Berry did come up with the song entirely by himself).

Ben 10: Race Against Time includes a bit of this. Eon seeks to use the Hands Of Armageddon to bring his Dying Race to Earth to repopulate, but traveling through time so much has weakened him to the point where he's unable to use the Hands. His plan is to use the Omnitrix to turn Ben into himself (a second Eon), so that he can activate the device and end the reign of humans on Earth. The movie is pretty vague about how it works, but at first glance, it seems as though Eon may actually be Ben, corrupted by himself in his own past. On top of that, when Eon succeeds in implanting himself in the Omnitrix, he declares that "two cannot exist at once", disappearing into a different point in the time stream.

Bill & Ted's Excellent Adventure establishes that "the clock is always running in San Dimas" — that is, that however long Bill and Ted are in another time, that much time will have passed when they return to their "home time". This is held up for the first film and most of the second... and then utterly discarded for the ending of Bogus Journey, where they zap away for 18 months and return seconds after they left. Of course, the first film kludges it a bit as well — when initially going back to their own time, they actually end up at the same point they left, and have to be told by Rufus that they need to dial 1 digit higher for the next day. Even more odd, Rufus never tells the two of them his name. They hear it from their future selves, who presumably heard it from their future selves who...

The Butterfly Effect has the events of roughly half of Evan's blackouts caused by his older self going back to them, while the other half were normal initially, but could be changed by his older self. One blackout even has examples of both. Also, it is established early on that Evan is the only who has any memory of the old timelines, but at one point another character notices a change in the timeline for no apparent reason.

Déjà Vu starts out well enough, but implies that the detective has already gone back in time and failed. In the original timeline, the love interest dies, and the hero's blood is all over her apartment. So apparently, in the original timeline, he went back and failed. But then in the new timeline, he gets his wounds saving the love interest. He doesn't bleed all over the love interest's place until after he saves her. So how did there end up being blood in the original timeline, but the love interests dies? What's more, the ending finishes without a Stable Time Loop of any kind, so either the changes made will reset or they've created one alternate timeline where everything is hunky dory and one where everyone's dead.

The time travel model used for this movie actually does make sense, it just creates convoluted timelines and is pretty confusing when watched without knowing this beforehand: https://en.wikipedia.org/wiki/File:Deja_Vu_Timeline.GIF#file The authors were pretty unhappy with the way the material was directed, saying that it made the film seem like it had many unforgivable plot holes even though there weren't any.

Detention has one of these as a result of several things: a mother and daughter undergoing a "Freaky Friday" Flip that sees the daughter transplanted into her mother's body circa 1992, another kid from the year 1992 undergoing a nineteen-year time warp to the present day (2011), and a nerdy Asian kid in the present day transforming the school's bear mascot into a time machine for a science project. Ultimately, it will result in the destruction of the world... actually, just the destruction of Grizzly Lake High School, because hey, it's not like the main characters know of a world beyond high school.

Frequency is one big Timey-Wimey Ball. You've got the son talking to the dad on the same ham radio, and even the whole "changes happen in sync with each other" deal. The first time John changes history and saves his father, he suddenly has memories of both timelines, which is promptly dropped for the rest of the film as from then on he only has memories of how things originally happened.

Hot Tub Time Machine is really inconsistent with its time travel mechanics. Four friends travel back to one day in 1986 and hijack their younger bodies, so everyone sees them as their younger selves. Except one of the friends - Jacob - wasn't born yet and looks the same in the past as he did in the present, and can also interact with the past, but whenever something happens that might possibly stop his conception he flickers out temporarily. Initially the friends, fearing the Butterfly of Doom, try to enact a Stable Time Loop by making sure the big events they remember from that night still happen, but then they change their minds and try to make sure the night goes better the second time around. Some of the big events they remember still happen no matter what they do, but no in the way they remember them. Other events they really do alter. Meanwhile they directly or indirectly cause a couple of historical changes. In the end Lou decides to stay behind and use his knowledge of the future to greatly improve his and everyone's lives. When the other three friends get back they all have much better lives but do not remember them.

The Lake House was a horrible mixture of Time Travel ideologies. In some ways the timeline is constant — the guy she kissed at the party turns out to be the guy she's communicating with in the past. Yet in other ways the timeline is variable — she tells him how she misses the trees, so he plants one at the place she's going to live at — which she magically doesn't notice having grown until after she sent him that letter. And then there's the grandfather paradox involving the (lack of a) car accident at the end/beginning of the film, causing her to go/not go to the lake house and end up communicating/not communicating with the guy in the first place. And there's also the dog in the past timeline who responded to the name given to it in the future timeline.

If you injure the present version of someone, the time-travelling-from-the-future version of the person will immediately show the scars. However, all events involving the future version up until the point the present version was injured continue to have happened as if the injury had never occurred. So you can cut off a present versions legs to stop the future one from escaping, and the future version will immediately fall over in a location they never could have reached unless they had legs up until a few seconds ago.

The trope is lampshaded on several occasions by the protagonists; criminals who don't really understand how the various time travel paradoxes work, only that trying to sort it out in their heads just gives you a headache.

Subverted in the extended version of the diner scene which is included as a DVD extra: after telling Young!Joe that he's not going to try to explain the effects of changing the past, Old!Joe then proceeds to explain them, using a line of salt — and it actually sorta makes sense.

Lost in Space contains a plot where John and Don walk into the future by an energy field just to find future Will and Dr. Smith creating that energy field as a result to build a machine to travel into the past, because the entire family was wiped out as a result of John and Don disappearing by walking into the future. When present Will and Dr. Smith enter the bubble, nothing happens to their future selves. Hell, Future Dr. Smith killed his past self without a second thought.

Project Almanac begins because David finds a video of his current day self at his seventh birthday party, which leads to him discovering and rebuilding the time machine stored in his father's basement, suggesting a Stable Time Loop. Immediately after doing this, however, the cast wantonly screws with their own timeline to make things more favorable for themselves, clearly demonstrating that time can also be changed at will. What's especially crazy is that the situation the video depicts is David retgonning himself by destroying the time machine, which he succeeds in doing, meaning the very situation that led them to the time machine originates from a timeline in which said machine does not exist.

The film version of A Sound of Thunder (if not the book) uses hilariously inconsistent rules of time travel (and those rules don't make much sense before they start breaking them). It's a crucial plot point that the characters keep returning to the exact same point in time, but never run into previous versions of themselves (no explanation for that is given)... until the time they do (no explanation for that either). Plants smash through the walls of a building because the past was changed in such a way as to cause plants to grow larger and more aggressively (no explanation is given as to why someone decided to build the building in the spot where, in the new timeline, a giant tree has been growing for ages — not to mention why the tree that's always been there smashes through the floor while people watch instead of just appearing as it if had always been there). At one point, the characters are unable to travel back to the point in time they want to reach because there's a time disturbance between the present and their destination in the past; the solution? Travel back to an even earlier point and then go forward (if you guessed that no explanation is given as to why the time disturbance is somehow not blocking that too, you've been paying attention). There were explanations - that the changes come in waves, changing things in fits and starts, not all as a whole. As for having to travel further back, that's easy to explain. Think of it as trying to get into a house, but the front door has something pressed against it stopping you from opening it. What do you do? Go in through the back door and then walk through the house to the front door to remove the blockage. Simples!

Star Trek: Word of God has it that instead of erasing the later series, it just split off a new timeline, so that the later series still happened in the original timeline (dubbed "the Prime" timeline in Fanon) but has not in the new timeline. This gets weird as there are many instances of characters from the Prime timeline traveling back to before the split, which means that if a character from the alternate timeline were to travel back to say, The orbital Atomic Accident, The Bell Riots, or The first Warp Test they would find time travelers from the Prime timeline, which from their point of view doesn't exist. Quite a Mind Screw... or Ass Pull, depending on the variance of your mileage. Prior to the film, Star Trek was pretty consistent that time travel changes affect the existing timeline, they don't spawn new timelines (though the existence of parallel but different realities were established, they just weren't caused by time-travel).

Star Trek: Generations, contains a nexus which can at once be described as a portal through time and simultaneously interpreted as a veritable heaven which may, in fact, act as merely a database containing the sentient thoughts of all who have encountered it. Kirk's visit to his past doesn't affect the timeline (although one may say this is due to him not actually doing anything to affect it). Picard, on the other hand, experiences an alternate present. While all this could seem viable as time travel, Guinan stops by to mention that Picard can experience the past or the future, the limits of his experiences within the nexus seemingly being restricted to his own imagination. This should leave a very Fridge Logic-taste in anyone's mouth when they realize that Picard and Kirk traveling back to stop Soren may not actually be time-travel but merely a pocket of Picard's own imagination within the nexus. Thus everything that happens past this point in time (i.e. First Contact, Insurrection and Nemesis) are not actually part of the prime timeline as Picard is actually gone and the Enterprise is destroyed with its crew dead. Note that the new timeline Star Trek could still be viable as there's no mention of Picard or Enterprise D and Generations has no effect on Spock's existence. Basically, if you accept the nexus as a means of time travel then the time line splits. If you argue it as merely Nexus-Picard's mind, then it doesn't.

Each Terminator movie uses a different theory of Time Travel, though it's at least consistent within each movie.

Though one persistent law of Time Travel is that things can only Time Travel is they are made of meat (so people, but not the organic fibers of clothing), wrapped in meat (i.e., Cyborg Terminators), can do a reasonably good imitation of meat (i.e., "Liquid Metal" Terminators) or sneak in when nobody's looking (Cromartie's head, which was still covered in meat). Which is to say, the mechanism here appears to be exactly analogous to airport security. The jury still is out on what would happen if you tried to bring a Ham and Fusion Grenade Sandwich with you.

This actually gets answered in the comic book continuity. A group of skinned-up Terminators gets sent back, but bring along an extremely fat human they captured because he's literally a meat bag. Full of guns. Whom the others have to kill to open.

The theory they use is that only living tissue can travel back in time. A deleted scene from the 2nd film indicates that the T1000 traveled back in a sack of living flesh and cut its way free before killing the cop. One inconsistency is a scene originally in the script for the first film indicates that Kyle Reese's partner, who travels back with him, gets fused into a fire escape and is instantly killed. Though as this is removed from the film it doesn't much affect the time portal energy cutting through things in the 2nd film.

Terminator Genisys goes whole hog on the Timey-Wimey Ball, as Kyle goes to 1984, and finds that the past has already changed thanks to SkyNet sending Terminators to try to kill Sarah when she was even younger. And that was caused by a Butterfly of Doomin the future - namely, Sknet attacking John while Kyle was going back through time. Entertainment Weeklytried to explain how things went (the writer even lampshades how complicated things get: "If I follow this correctly—and I admit that my nose is bleeding while I type this...").

In The Film of the BookThe Time Machine (2002), the Time Traveler discovers that he cannot change any part of the past that would interfere with him creating the Time Machine, since it would create a Temporal Paradox. He can interfere with other matters, such as when he goes even further into the future only to see the Morlocks victorious over the Eloi, and afterward returns to the year 802701 to successfully defeat the Morlocks.

James P. Hogan had a solution in Thrice Upon a Time. The prospective time traveler induces a grandfather paradox. The universe doesn't abhor it or disallow it or anything, but simply plays out the umpteen zillion iterations of the events in question. A leads to B leads to Not-A leads to Not-B leads to A leads to B... It should go on forever, but on each run-through, quantum randomness causes things to be very, very slightly different (an atom decays or not, a pair of colliding air particle zig instead of zag) totally regardless of anything the time traveler does. Normally they won't make any difference whatsoever, but after a few million or trillion iterations, the randomness happens to align in such a way that it breaks the paradox (i.e., kills his wife in a new way) and lets the timeline continue past it. What we the audience see is merely the "final cut" version of history, the one that didn't get stuck in an endless loop.

Time Chasers, which 99 percent of its viewers know from Mystery Science Theater 3000. It tells - or rather, tries to tell - the story a man who invents a time-traveling airplane who has to repeatedly go back and stop his former boss from stealing and exploiting his invention for his own personal gain.

Literature

11/22/63 gets...vague with how time travel works. At first at seems like traveling to the past always creates a fresh new timeline, or "string," where none of your other trips happened, and if you screw something up, you can always make a new string where you didn't. However, it turns out that the strings can become tangled if there are too many of them, and making changes to history is like plucking the strings, causing them to "harmonize" with each other. If you get too many strings harmonizing, time itself will shatter from the vibrations. Jake nearly causes this to happen by saving JFK's life, but somehow he's able to save the world by making another string where that doesn't happen. All of this is explained by a hobo who's been driven insane by a very nasty version of Ripple Effect-Proof Memory (imagine remembering hundreds of different futures all at once, all in equal clarity) so there's a lot the reader never finds out.

Animorphs made use of Time Travel occasionally, and each time it apparently worked differently. Different techniques of Time Travel were involved, at least one of which was by use of a thingy created by the closest thing to a God in the series, and another (a Bad Future-esque thing) was just flat-out never explained. The bad future was apparently a dream caused by an advanced being for some reason. Maybe.

Eoin Colfer's Artemis Fowl and the Time Paradoxdoes not actually feature any paradoxes. The prequel on the other hand... Specifically, an island was magically removed from normal time for 10,000 years, but the magic is breaking up and time starts running alternately forward and backward at varying speeds. Holly dies, but Artemis fires a shot backwards in time thus killing the demon who killed her and bringing her back to life. Furthermore, Artemis goes back in time and causes a mosaic of himself to be created hundreds of years in the past, a fact which is only noticed in the present day after he gets back. Artemis questions the first paradox, but eventually gives up trying to figure it out.

In Last Guardian Opal defies Stable Time Loop by having her past self from Time Paradox killed, and manages to survive. What Opal's timeline looks like now is anyone's guess.

The Book of All Hours duology by Hal Duncan doesn't even try to claim to be otherwise. It's such a mishmash of pocket universes, alternate universes, and paradox that causality can't even be seen with a telescope on a good day. Essentially: think of the universe as a huge piece of vellum on which reality has been written. Then crumple it up. Most characters make such a habit of going not just back and forth in time but sideways that one goes back to the day where he, as a child, met his elder self, and that elder self committed suicide... only now, as the elder self, shoots his younger self instead. Nothing happens to the elder.

In Connie Willis's stories, the time machine sends you not to your target time-and-place but to the nearest point such that your actions will not change history. (This is consistent with James Hogan's theory mentioned above, though the mechanism is not explicitly stated.) In Doomsday Book (which shared the Hugo Award in 1993), a history student aiming for England 1328 lands instead in 1348, where she can't affect history because everyone she meets will shortly be dead of the Plague.

In Thief of Time, it's revealed that, following various alterations to the Disc's temporal dimensions, the "true history" barely exists, and their main job is to prevent the Timey-Wimey Ball from imploding.

In Night Watch, when Vimes travels thirty years into the past to become his own mentor, even the monks aren't sure what's happening.

Lu-Tze: For a perfectly logical chain of reasons, Vimes ended back in time even looking rather like Keel! Eyepatch and scar! Is that Narrative Causality, or Historical Imperative, or Just Plain Weird?

If you try to place the times and events of some books, you will find they take place a couple years before a different book, and at the same time, hundreds of years before the IMMEDIATE SEQUEL of that different book.

Sir Terry himself at one point explained that "There are no inconsistencies in the Discworld books; occasionally, however, there are alternate pasts."

Jack Chalker's Downtiming the Nightside: People leaping through time can affect changes. If the change is small enough, nothing much happens to the timeline, but significant changes can happen. Karl Marx is killed 3 different times, at 3 different points of his life. At the end of his life, not too significant. After he publishes Das Kapital, not too bad either. Before he publishes it on the other hand... And this is just the tip of the timey-wimey iceberg.

In Johnny and the Bomb, Pratchett explains that most time travellers forget the original timeline when they return to the new one because of the human tendency to accept what's around them as normal; but if you really try (or are reminded of it by some useful clue) you can remember how things used to be.

David Gerrold's The Man Who Folded Himself features a time-travel belt, which has the traveller completely paranoid about the possibility of a Temporal Paradox destroying him. It turns out that Temporal Paradoxes are impossible; Time Travel rewrites history except for the guy who travelled through time. Various Mind Screw moments: the protagonist has orgies with himself of different ages, writes himself out of history, has a family with himself as a female, eventually has that written out of history (but his son still exists) and culminates in finally giving himself (as the son, so he's his own father) the time travel device. On the last, the idea of where it came from is explored a couple of times and eventually it's hit upon that it's impossible to know where it came from, the creators must have been written out of history. Oh, and he kills Jesus at an early age. It's okay, he goes back and stops himself after finding out how much it screws with history.

Time Patrol stories are historically well-researched and confusing as hell. Among other things, the future is "uptime" and the past is "downtime," which makes it sound counterintuitively like time is a river that flows uphill. (This is consistent with convention in geology and archeology, where an earlier period is "lower" because its evidence is in deeper strata.)

Ditto in the 1632 series, the Grantville inhabitants from 2000 are "uptimers," the seventeenth century natives are "downtimers."

The same terminology is used in The End of Eternity, where use words like "downwhen", "upwhen", "anywhen" and "everywhen".

The Last Dragon Chronicles: Oh God. There are too many examples to list, though things start getting particularly crazy from Dark Fire onward. Taken to extremes in The Fire Ascending.

Dean Koontz averted some time travel issues in Lightning by virtue of having the Nazis invent time travel, the limitation being that it can only send you forward (and then you snap back to your point of origin when you make the return trip). While this has its own problems, it at least eliminates the ability to murder your mother before she gave birth to you. You cannot change your own past, but you can change the past of anyone born after you so long as the changes you try to make are not contradictory, and you can bring objects back. Played straight in that if a contradiction is demanded, the portal will refuse the forward transfer (this gets the heroine killed in one timeline). "Destiny struggles to reassert the pattern that was meant to be." Sometimes happily, and sometimes not so happily, it succeeds.

The Never Again series starts out simple enough. It seems to follow the many-worlds interpretation of quantum mechanics so that time travelers can do anything they want, but will create a new timeline that never intersects with the old. Then comes the third book, where that is thrown out the window, and the author's attempts to explain what is happening (with a lot of Technobabble about "intersecting universes" and the like) just raises further questions.

The character of Phanthro in Relativity is a time-traveller from the distant future. He's constantly altering history (for the fun of it). When he's asked how he can alter the past without wiping his own time period out of existence, he just says, "Time doesn't work that way." No further explanation is ever given.

Heinlein wrote a short story called By His Bootstraps, in which the protagonist exploits a time machine to move himself forward in time. Simple enough. The Mind Screw comes in when he does this by his future self sending back his intermediate self to persuade his past self to enter the machine's portal. When the past self becomes the intermediate self, he attempts to double cross the future self, but that double cross naturally results in him becoming the future self. Follow all that?

For a real, double whammy version of mind screw, read —All You Zombies— which chronicles a young man (later revealed to be post-real-sex change) taken back in time and tricked into impregnating his younger, female self (before s/he underwent said sex change); then he turns out to be the offspring of that union (time-relocated yet again), with the paradoxical result that he is both his own mother and father. As the story unfolds, all the major characters — the young single mother, her seducer, the alcoholic writer, the bartender who recruits him into the time-travel corps, and even the baby — are revealed to be the same person, at different stages of her/his life. How's your mind doing now?

Harry Harrison's The Stainless Steel Rat Saves the World features two overlapping timelines (one of which only has a temporary existence) and a loop. The lead character travels back in time to stop the Special Corps being removed from history, and manages to disrupt the enemy's plan. He then follows them further back in time, landing in an alternate history where Napoleon conquered Britain. He messes up the controls on the enemy time machine, and (after being rescued shortly before the alternate history disappears) follows them forward (but still long before his own time). He finds the villains (after a long time for them — so long they've forgotten everything except that he's the Enemy), but is unable to stop them; they travel back in time, and he's only saved by a time machine — allowing him to return to his own time — which he then sends back with the instructions for what he just did. Finally, he's told not to worry that he didn't stop the villains; they've just travelled to the first place he met them, where they will then travel back and create an alternate history where Napoleon conquered Britain, before...

Star Trek: The novel Q-Squared introduces several alternate realities, including one based on the Bad Future in Yesterday's Enterprise. However, in this case, when the Ent-D finds the Ent-C, all the crew aboard it are already dead. Afraid of Klingons getting their hands on a Federation warship (even an old one), they scuttle it and move on. Oh, and by the end of the novel, that reality is even worse off, since its Picard and Riker are dead.

In A Tale of Time City by Diana Wynne Jones, the titular city exists outside of the flow of history on the rest of the world. From this vantage point, the citizens see that history works like weather patterns — it shifts back and forth with minute details thanks to the butterfly effect and time loops. Basically, a more detailed explanation of the Timey-Wimey Ball, where shifts in the time travel theories are explained away as the changing "weather patterns" of time. For instance, on one day in Time City the inhabitants may observe that World War II begins in 1939, but on another day they may notice that it has changed to 1938. Perhaps time in the book is two-dimensional, with Time City time orthogonal to time everywhere else. Except it turns out that the history of Time City can shift back and forth too...

In Jasper Fforde's Thursday Next novels, not only do the rules of Time Travel make no sense whatsoever, the main character (whose father is a time-traveller) realises this, and often lampshades it. In one book, the rules actually seem to change over the course of a conversation with her dad, but she realizes there's no point in even asking.

In First Among Sequels, there is a subplot revolving around the fact that the time-travellers have mapped almost the entire future and found that Time Travel has not yet been invented. By the end of the book, Thursday and co. have managed to ensure that Time Travel is never invented, and thus, could never have been used earlier in the series. This means that several events from the previous four books including the plays of William Shakespeareand the beginning of all life on earth logically could not have happened. Since many of these events were the results of Stable Time Loops anyway, this is a case of Ascended Time Paradox. Or Mind Screw turned Up to 11. Either way, it's probably best just to apply the MST3K Mantra and enjoy the series.

A significant part of the plot of The Woman Who Died a Lot is that the non-existence of time travel in a world where many people know they used to work for the ChronoGuard has actually made the Timey-Wimey Ball worse.

In We Can't Rewind, the narrator makes several attempts to make sense of how his world's peculiar form of time travel works for the readers, and then gives up, explaining that he'll probably lose his mind if he keeps this up for much longer. He mentions that the temporal theorists of Merciar, from which he's writing this account, are doing no better at settling their controversies over how exactly inter-dimensional time travel works, and that most of Merciar's citizens have already given up trying to make sense of it in order to preserve their sanity and advised everyone else to do the same.

World of Warcraft: The novel trilogy War of the Ancients. Despite some dramatic changes (such as saving an entire race that originally went extinct), it's apparently okay to mess with time as long as the end result is roughly the same. Of course, it also helps explaining why said race appears rather plentiful in World of Warcraft after having been said to be extinct in an earlier novel...

Live-Action TV

12 Monkeys: Cole is only chosen for the time-travel mission because there is a recording of Cassandra recovered in 2043 where she mentions him by name, implying some kind of Stable Time Loop is involved (Jones herself says that Cole's destiny is "preordained"). Yet, the entire premise of the series ( unlike the original film) is that history is mutable and that the past can be re-written (which is clearly demonstrated when Cole scratches Cassandra's watch, causing a scratch to simultaneously appear on its future counterpart).

The events of the first season of The Flash (2014) were kickstarted by Prof. Eobard Thawne a.k.a. the Reverse Flash going back in time and killing Nora Allen. He also spends most of the season trying to get back to the future and it's heavily implied that he wants to go back to the same future he left despite going back a century and causing massive changes.

Later in the first season Flash performs Mental Time Travel going back a day despite it being already established that Reverse Flash physically traveled back in time.

Then season finale came and Barry was supposed to perform physical time travel and prevent his mother from dying by running at mach 2 and getting hit by a hydrogen particle. At the same time, Reverse Flash planned to use Barry's travel to get back to the future in some machine he somehow didn't need the first time and is definitely not needed by Barry. Long story short, Eobard's ancestor Eddie got killed, which erased Eobard from existence, since he'd never be born, but it somehow didn't affect anything that he did throughout the season. Oh, and as a result, a black hole appeared over Central City, threatening to destroy the Earth.

Then Reverse Flash returned in season 2 despite never having been born. This was explained by him being protected by some "time bubble" or whatever during his "earlier" time travels. When he gets locked in the pipeline and stopped from going back to the future (from which he would have time traveled again to cause Season 1 to happen) metahuman Vibe is somehow getting erased from existence supposedly because he got powers from Reverse Flash causing the explosion of the particle accelerator. For some reason, only Vibe is affected despite every metahuman getting his/her powers this way. Flash has to get Reverse Flash back to the future to save Vibe and yet this time it's achieved merely by running fast enough without using the hydrogen particle.

Then Legends of Tomorrow came and things got even messier. Not only Rip Hunter mentions "fixed points in time" which cannot be changed for some reason, but also it is said that changing the future is harder than changing the past, never mind that "future" in question is actually his past, and that future is completely arbitrary concept in time travel in the first place; it depends on what you call the present. It also mentions nasty aftereffects for health of time travelers, which neither Flash nor Reverse-Flash ever experienced.

Actually it makes sense that speedsters dont experience any side-effects as they are protected by the speed force when time traveling. It wouldn't make sense if the Speed Force could protect them from something as severe as paradoxes and never being born but couldn't protect them from nausea, blindness or anything so mundane.

Got even weirder in the Season 1 finale. Vandal Savage plots to set off explosions at three points in time to reset history back thousands of years and do it over. Somehow, stopping and killing his youngest self won't help; the Legends have to stop all three of him.

In Season 2 it get's even more convoluted when the Legion of Doom acquires the Spear of Destiny, an item that can alter reality, and use it to create a perfect world (for them) and change the entire timeline. And despite the past being changed too via this, the Legends are still somehow able to travel back in time to a point where time hasn't been altered yet.

Then all logic is thrown out of the whole thing at the end of Season 2 of Flash. Barry goes back in time again to prevent his mother's death and succeeds, in effect just undoing all the changes Reverse Flash caused in the first place. The 3rd season opens with the Flashpoint timeline, a timeline where of course Barry's parents are still alive, but the particle accelerator explosion happened early somehow anyway even though Thawne is the one that made that happen, there are metahumans running around as a result, Wally is The Flash instead of Barry, Barry is gradually losing his memories because in this timeline he never got them for some reason, Joe is a hopeless drunk barely hanging onto his job, while Cisco is filthy rich and Caitlin is a pediatric ophthalmologist. It gets even MORE confusing when Barry subsequently reverses his change, which instead of ending up right back in the timeline as he left it resulted in a timeline where Thawne somehow never became trapped in the past thus should have resulted in the events of the first 2 seasons never happening but again they do anyway, Cisco's brother died in a car crash, Caitlin now is developing ice powers, Joe and Iris are on the outs, Barry has a partner at work that never was there before, and there's a supervillain running around giving people who had powers back in Flashpoint powers again for some reason and yet another speedster supervillain behind that.

Savitar, the Season 3 Big Bad who turns out to be a future duplicate of Barry who only exists because of a Stable Time Loop, eventually hangs a big fat lampshade on this mess, when he states that the more speedsters use time travel, the less the rules apply to them anyway.

Once The Multiverse is added to the equation, it somehow becomes that temporal alterations in one world have zero effect on the others, even though they may have intersected at one point. For example, post-Flashpoint, when Harry and Jesse return to Earth-1, they immediately note certain differences, which weren't there pre-Flashpoint.

Then in Legends, Thawne ends up being once again erased from existence by the Black Flash... only to somehow come back and end up on Earth-X, once again wearing the face of Dr. Wells. When asked, even he's not sure how it happened. When Barry has him cornered, he decides not to kill him, possibly acknowledging that Thawne will just return anyway.

Oh, and both times Thawne comes back to life, he acts as if he has lived those 15 years in the guise of Harrison Wells, even though the time remnant version of him that hasn't experienced those events.

Black Hole High: "Fate": When Vaughn, having traveled back in time to meet his mother, steals her hairclip as a memento, all of history is rewritten so that his parents never meet, his father becomes a familyless loser instead of creating the wormhole, and Professor Z doesn't get a scholarship from his company to go to college. Which is all well and good. What no one attempts to explain is why, in this new history, Josie never attended Blake Holsey High (Though later events suggest that her presence there may have been engineered to keep her close to the wormhole). To complicate matters further, it eventually turns out that both Vaughn's mother and Josie's father are time travelers, so without Pearson's wormhole (the basis for Time Travel), Josie shouldn't exist either.

In Season 8 of Buffy the Vampire Slayer, Future Dark Willow exploits the time travel confusion for all it's worth to manipulate people to her advantage.

In one episode, Chris is taken 20 years into the future as a prisoner by a bunch of evil dudes. Before he leaves, he manages to slip in a comment about the "creaky floorboard". The witches take the hint and brew a potion for him to use as a weapon, which they hide under said floorboard. The camera goes back and forth, showing what is happening in the future (Chris facing the bad guys) and the present (the girls hurrying to finish the potion). It's strongly implied that, had they not gotten the potion ready in time (i.e. before Chris in the future is shown looking under the floorboard), Chris would have found nothing. In actual fact though, the girls could have relaxed and spent hours making the potion, it would still have been there 20 years into the future, provided it was never removed from under the floorboard at a later time. Speaking of which, the writers may just have assumed the potion would be gone after the episode, rather than continually being under that floorboard for the next 20 years.

In another episode, a demon steals little 3-year-old Wyatt's magic powers. Next thing, 20-year-old Wyatt and his brother come time-travelling from the future, saying "We were fighting demons when Wyatt suddenly lost his powers, so we thought we'd come to the point in time where the change occurred and see what happened". This makes no sense in any form of time travel. If 3-year-old Wyatt lost his powers, then 4-year-old and 5-year-old Wyatt wouldn't have had any powers either, all the way up to 20-year-old Wyatt. It would make no sense for him to loose his powers only suddenly at the age of twenty. Not to mention, once they fixed the problem in the present, 20-year-old Wyatt should have never lost his powers in his time at all.

In another, Chris (having time traveled back to the show's present from the future) is corrupted by demonic influence. They make an antidote for it and Piper, who is pregnant with Chris at the time, drinks the potion. Naturally, this cures the adult Chris after she drinks it rather than preventing him from being corrupted in the first place.

Continuum has a literal Timey-Wimey ball, since there are eight pieces that magnetically grab onto each other and when they do so in the presence of sufficient power, it activates and zaps anyone within a certain radius to a new destination time.

Barnabas Collins travels back in time to save Collinwood from the ghost of Quentin. When he returns, Amy and David still remember being tormented by Quentin's ghost, despite the fact that with the change in history, Quentin never died and is still alive.

Despite the times Barnabas is released from his coffin when he travels back to 1897, and then to 1840, he still has a history with the Collins family in the present era.

The fact that Quentin, Tad, and Desmond Collins survived in 1840, thanks to Barnabas and Julia, changing the line of inheritance, does not seem to have any impact on the Collins family in the present day.

The Ghosts Of Motley Hall a series told from the point of view of the ghosts from various eras who haunt a derelict stately home in England discover one Christmas that, for no reason ever explained, the house has slipped through time to the Victorian era. The ghost of Sir George meets and talks to a young boy who is excited about his presents. Sir George realizes the boy is himself, and only then recalls a vague memory of having met an elderly man on Christmas Eve, who he had assumed to be some distant relative whom he never saw again.

The Girl from Tomorrow has a very large one: Tulista travels back through time and retrieves Silverthorn. Taking him out of the timeline should screw with the future, but doesn't, thanks to one very Delayed Ripple Effect. Silverthorn then takes Alana back to 1990, and their presence in the timeline again fails to interfere with the future properly. It's only after Alana takes them both back to the year 3000 that people begin to notice the Delayed Ripple Effect, despite the fact that if anything, it should have interfered with two time periods. They then attempt to resolve this by returning Silverthorn and Jenny to their respective time periods, only to have the capsule somehow U-turn and return to 2500, meaning there are (briefly) duplicates of Alana and Lorien. This is further compounded when Silverthorn builds a Portal to the Past to get some nuclear bombs. This is only resolved when Petey resets the Portal to send Silverthorn and Draco to 70,000,000 BC. Given what Petey says at the end of the series and the events during "Tomorrow's End", it looks like the entire series is actually a Stable Time Loop.

Heroes can't decide if they are going for Static Time Travelling or a Dynamic Time Travelling. And that's the least problematic thing.

Strangely, it seems the farther into the future they see, the more pliable time becomes. For example, if Hiro tries to fix something close to the present, for example, saving Charlie's life, or capturing Usutsu, it's impossible. Can't change it no matter how hard they try. However, the apocalyptic future they inevitably go to in every single season so far, they always find a way to avert that. Well, usually, that seems to be changing for season three, and even before that, some things were constant across all the alternate futures. Peter's scar, and Hiro being badass with a sword.

The Charlie issue was kind of resolved in a "she's already dying" way rather than "time travel won't let me save her" way; this is more or less repeated with his father in the next season (only "it's his time" this time, instead of the already dying thing). As for the random jumps through time... he spends the rest of the season learning to control his ability; it turns out he just needed to get back the self-confidence which he had lost since he realized he couldn't save Charlie. The time jumps are a bit convenient, and that Hiro's explanation makes no sense doesn't help. Not to mention that nothing else they've done with time travel has made any sense. They don't even try to be consistent, it seems. Very comic booky... which is probably the point. Still makes for bad headaches, point or no.

However, The Heroes novel Saving Charlie took the opposite tactic, implying that Time/God wouldn't let Hiro save Charlie because You Can't Fight Fate. Over the course of the story, Hiro lost control of his powers several times in the past while he was trying to romance Charlie and wound up "jumping" to key locations relating to his quest to save Claire Bennet. Eventually, Charlie figures out what is going on, tells Hiro he must face his destiny even if it doesn't involve her and the two lose their virginity together the evening before Charlie goes into work, meets Hiro for the first time and then gets killed by Sylar.

THEN HE SAVED CHARLIE. No, really. Seasons later, Hiro goes back in time, and gets none other than Sylar (the season one Sylar who'd never toyed with the idea of a Heel–Face Turn) to repair Charlie's aneurysm telekinetically and leave her brains on the inside in exchange for non-Time Crash-inducing information about his own future. However, she's kidnapped by the Big Bad of that season, and Hiro doesn't see her again until she's an old woman who's lived a happy life that Hiro wasn't going to undo so he could have her. Still, it was pretty awesome to see Hiro turn "You Can't Fight Fate" into "Up yours, fate!"

According to The Other Wiki, Hiro can change history as long as he doesn't eliminate his own cause for traveling in time. However, while this rule is sometimes played straight (he can't simply teleport Sylar away, as that would prevent him from meeting Charlie in the first place and he couldn't save her) but other times... not so much (his attempts to save the suicidal employee would eliminate his reason for time travel but it never works out that way. Of course, history doesn't actually wind up changing in that case, so it may not be a contradiction after all).

When an Imagin wreaks havoc in the past, it's translated into the present oddly. For example, if you were standing next to a bridge support, and an Imagin went to last year and broke it, you would see it vanish into thin air now (as opposed to, say, remembering that time a year ago when they had to fix the bridge 'cause a monster trashed it). But since it was trashed in the past, it had to have been rebuilt at some point, right? Apparently, when an Imagin breaks something, the fix's Ontological Inertia fails shortly after the time the Imagin went back. Now that's the Timey-Wimey Ball at its wibbly-wobbliest.

When the Imagin is killed, the Timey-Wimey Ball then uses the original memories of people in the future to repair the damage to the past. However, anything or anyone who is not remembered is not restored. So now no-one remembers the bridge getting repaired because as far as the great unwashed masses know, it was never broken in the first place.

In the crossover movie OOO, Den-O, All Riders: Let's Go Kamen Riders, an elaborate Temporal Paradox was revealed when we learned Naoki is Mitsuru's father. They didn't even try to explain it. This is a paradox because Naoki was stranded in the past after time had already been changed. The version of 1973 that led to the 2010 we know did not have Naoki in it. Therefore, Mitsurushould not exist in the 2010 we know.

The original Kamen Rider has two friends of Goro's by the names of... Naoki and Mitsuru. We meet them in the latter third of the series. Whether Let's Go Kamen Riders is trying to say that they are the same ones and we didn't know they were time travellers is hard to tell, but if that's what it means, it's certainly interesting. However, this adds another level to the timey-wimey: a 1973 with Let's Go Kamen Riders having happened led to the Kamen Rider universe proceeding in the manner we saw in the older shows, even though the whole movie is that the Den-Liner gang's trip leads to a Bad Future which got a happy ending in the present, but can't ever be erased.

When a Mad Scientist/Children's TV host proposes that everyone's lives are strings and if you could tie the ends together you should be able to travel along that string, Sam agrees that he is basically right, but that it is important that you ball up that string first so that all the days of your life touch. Which makes sense.

This also brings up a Stable Time Loop. Sam as a young boy sent the letter that the host reads on air at the end of the show, which prompts him to provide the explanation that Sam had previously given the host to make travel across one's lifetime work. It was that explanation that he watched given to his letter that inspired and guided Sam's research into time travel and create the Quantum Leap program to go back in time and create the event that led to him being able to go back in time.

As revealed in the finale, all time travel is monitored by God to create the best possible timeline and presumably keeps Leapers and good people from being erased by paradox and such.

Just about any time travel episode, but most especially the Season 6 cliffhanger in which the Dwarfers' scary future selves blow up Starbug, apparently killing everyone on board. Season 7 opens with Lister explaining direct to camera that, because they'd been killed, their future selves never existed to come back, therefore they hadn't been killed, and this is also why Starbug is suddenly bigger. The intelligent video camera suffers an explosive breakdown trying to understand this.

Ironically, Rimmer's plan in the cliffhanger episode, which was to destroy the Time Drive so that their future selves couldn't come back to kill them, would have made far more sense as an explanation.

And later in that same episode, The Boys From the Dwarf violate the same laws that allowed them to survive after they take John F. Kennedy back in time to assassinate his past self!

7Days. It is a rather harsh ground here, since the time machine is alien technology that was badly fixed by humans and due to possibly some screw up (or just plot convenience) it has all kinds of weird side effects. Anyway, when it works like it is supposed to do, it sends you back seven days and your old self and the time machine vanish, either erasing the "bad" timeline or creating an alternate. It is consistent in that. People notice the machine and him vanishing, the episodes are just mostly centered on Parker and until he makes his call they don't know what happened.

There was an episode where an accident during time travel splits Parker into a good and an evil version. The good version is killed, so the evil version is sent back in time again, creating another good version.

It's difficult to count the number of times the machine has not worked right. For just a few examples: it brought a person back from the dead (nearly unraveling all of reality), put Parker into the body of Pope John Paul II, created a Mirror Universe (almost literally, since all writing is in mirrored English), etc. It's a wonder the aliens don't show up to tell the humans to stop messing around with technology they don't understand before they destroy the universe. Then again, they probably don't know and have never bothered to look for their missing prison transport (or that other ship that crashed in Siberia).

The Stargate SG-1 episode "1969" dealt with a Stable Time Loop. Following that, however, all the Stargate series have just treated time travel as only affecting things after the initial entry point. Time is changed in both "2010" and "Moebius" without creating a stable loop. Same with "Unending". The DVD movie Continuum is a bit more complex, since it added a new element to the mix, but ultimately results in the same thing.

Stargate Atlantis had two episodes in the vein of "2010" and "Moebius", following pretty much the exact same conventions in both.

Stargate Universe also sticks to the formula, first with the episode "Time". A Kino is found, which has a recording of horrible death. This recording shows a way to avert it, but they fail to do so and send a second Kino back. That one, along with the first, does the job. Then comes "Twin Destinies". In this one, a wormhole connected to Earth from inside a star somehow catapults the entire ship back in time. Telford (In the time shifted ship) goes through the gate and makes it back to Earth, while the rest of the crew (except Rush) go through when the gate is unstable and get transported to a local stargate hundreds of years in the past while leaving behind Rush, who stays on the ship. The current timeline crew stripped the time-displaced copy for parts, while the extra Rush and the original Telford on Destiny died. Meanwhile the version of the crew sent into the past establishes the civilization of Novus, leading to the present day crew eventually meeting their own descendents in the following two parter.

The series has the relation between Benjamin Sisko and The Prophets. While it appears to be a Stable Time Loop, there just enough wrong with it that it fits here. In the first episode, Sisko meets The Prophets, who live outside of time, and have great difficulty even conceiving of a 'linear' existence. They and Sisko have a nice chat, and Sisko tells them that the Bajorans revere them as gods, it seems that The Prophets weren't really aware of this. It gets tricky from here... As the Prophets seem to 'get' their position, they then (not that the flow of time should mean anything here...) start doing all the things that they are revered as gods for. Okay, one loop, fairly simple Ontological Paradox. Later on, viewers find out that Sisko was born from a relationship his father had with a woman possessed by a Prophet with the explicit purpose of conceiving Sisko. So, Sisko visiting the Prophets made it possible for him to be born in the first place, so that he could visit the Prophets and tell them that they were gods. Keep in mind that if Sisko didn't tell them they were gods, they wouldn't need Sisko, they would have just kept on being non-linear, not to mention the enormous effect the resulting lack of religion would have on Bajor. Now what really twists the boat is that The Prophets are supposed to exist outside time, yet they clearly change after Sisko's first meeting. So they possess both timelessness (from being able to interact with anytime freely) and their own timeline (Which is clearly affected by Siskos visit) These paradoxes and timey-wimey balls are not really explored in the series (though more 'common' forms of time travel are) and the series can be enjoyed without worrying about the timeline of timeless entities. Still, there's rather a lack of coherency.

The whole thing gets kind of lampshaded, when two versions of O'Brien try to figure out the paradoxes and give it up, simultaneously saying, "I hate temporal mechanics!" The episode in question, "Visionary", is quite Timey-Wimey in itself, as O'Brien keeps jumping five hours into the future and back, with varying changes once the station reaches that point he jumped to. He even avoids death twice, first by avoiding a booby-trapped surveillance device that killed his future self, then by having Dr. Bashir perform a specific scan on him after finding out the results of his own autopsy. In the final jump, though, Past!O'Brien ends up dying from radiation poisoning, sending Future!O'Brien back 3 1/2 hours to stop the Romulan attack on the station. The resulting O'Brien has issues with his place in the universe for a while afterward.

Star Trek: Deep Space Nine's Sisko and his companions are visited by the Department of Temporal Investigations in Trials and Tribble-ations. The agents mention that they have an extensive file on captain James T. Kirk. They also hate Predestination Paradoxes and jokes.

This episode also involves a literal Timey-Wimey Ball, the "Orb of Time"

Another episode had the Prophets bring a famous Bajoran poet forward in time. After they sent him back, all the copies of his famous unfinished poem suddenly showed it as finished. The characters understand that part, but they never figure out how the Prophets made it so that it still hadn't been complete until after his visit. So there's a timeline where he disappeared into the future, and then after he went back there's a timeline where he went back, but somehow the second doesn't overwrite the first it just picks up where the first left off.

Star Trek: Enterprise: The whole Xindi arc is a big example. So the Sphere Builders tell the Xindi to go nuke Earth, because they know (through their semi-time-travel) that in the 26th century, Earth will come kick their ass. So the Xindi go do a preliminary Earth nuking, which causes the Humans to come over and kick their ass, now. The Sphere Builders misled the Xindi into believing that humanity will destroy the new Xindi homeworld, because the Sphere Builders knew that, in the 26th Century, the Federation (which by then will include the Xindi) will decisively defeat the Sphere Builders at Procyon V.

In the 29th century, The Federation has become a sort of Time Police, making sure no one messes with history. The fact that the previous (chronologically) series have never had a problem with timecops showing up is not addressed. They were even admonished that they ought to have been held to account before. Not to mention, if they did, the audience would never know about it...note Mind you, if 29th century The Federation were to start messing with events that happened in their past, that would itself create a time paradox, and thus their own rules prohibit them from policing any temporal incursions that occurred prior to their becoming the Time Police.

The episode contained the morally questionable practice of arresting and trying a man for a crime he had yet to commit. The rather profound implications of this are casually handwaved with an assurance that he'll be combined with his future selves somehow before the trial, never mind that said future selves are already part of a Temporal Paradox since it would presumably be impossible for him to carry out the crime once he'd been arrested for it. This might not be so troubling if it weren't clear that his future selves were suffering from some kind of severe psychological breakdown, the present self would not decide to commit the crime for many years and thus could not be said to have intent, and being removed from command at this early point would have prevented said psychological breakdown from occurring in the first place. Given equal apparent opportunity to prevent someone from becoming a criminal before it was too late, or punishing him for merely being capable, under the right circumstances, of going through with it, which would you choose? Apparently The Federation, at least according to Voyager's writers, prefers the latter. And the guy's future self was only mentally unstable because said Time Police had already "somehow combined" him with yet another version from an alternate timeline, who had been stranded for decades as a homeless guy on 20th century Earth. One would think they'd get the hint that "combining" people from different timelines is a bad idea...

Star Trek: Voyager also had one of the most illogical time travel plots. They're passing a planet and detect a massive explosion. They investigate the planet and find no life. Janeway and Paris are transported back to before the explosion. It turns out that Voyager's attempts to reclaim them caused the explosion. Janeway stops their next attempt by firing her phaser into the time-portal technobabble thingy, which pushes the Reset Button and they pass the planet without incident. The entire episode ignores that they never intended to go to the planet in the first place, so the whole thing never should have gotten started, since there never would have been an explosion to cause them to investigate.

Also a major question mark inherent in the finale episode "Endgame". Admiral Janeway from 2404 decides to go back and change the past because three of her favorite crew members did not get happy endings due to Voyager's decades-long journey home. To achieve this she needs help from her old crew (and one of their daughters). The problem of everybody having the last few decades of their lives erased and replaced with an uncertain alternate timeline engineered by Janeway is kind of glossed over, leaving the question of whether she actually changed history or simply created a new timeline.

A quote from Jonathan Frakes re: Yesterday's Enterprise: "To this day I do not understand Yesterday's Enterprise. I do not know what the fuck happened in that episode. I'm still trying to understand it ... but I liked the look." This would become pretty darn Hilarious in Hindsight, given his Trek cinematic directorial debut featured both time travel and a revamped color scheme for the Enterprise.

This one isn't all that hard as far as paradoxes go. During the Battle of Narendra III, the Enterprise-C made a Heroic Sacrifice against the Romulans attacking the Klingon outpost. This is exactly the kind of honorable, selfless action that would impress a Proud Warrior Race like the Klingons and eventually led to a peace treaty between them and the Federation. However, during the battle, a massive explosion caused a Negative Space Wedgie to form, sending the Enterprise-C to the present. But without the Enterprise-C's presence at the battle, the peace treaty would have never formed, either because their sacrifice made the necessary improvements or their disappearance convinced the Klingons that the Federation were Dirty Cowards and things got worse. So once the Enterprise-C arrives in the present, the present almost immediately becomes a Bad Future where the Federation and Klingon Empire have been at war for decades. As a Klingon, Worf was probably dead as the Enterprise-C wasn't there to defend his colony and he certainly wasn't rescued by Sergey Rozhenko. Tasha Yar is presumably alive because the Enterprise-D never went to the planet she died on, because it is a warship not an exploration ship. The Enterprise-D helps repair the -C enough to send it back through so it can be destroyed as it should have. But Tasha Yar discovers from Guinean (who has some alteration-proof sense of how the timeline is supposed to be) that she died a pointless death in the "normal" timeline. So she volunteers to go back with the understaffed -C. The Enterprise-C goes back to the Battle of Narendra III and is destroyed. It's revealed later that the Romulans captured several survivors, including Tasha from the war-timeline. So all in all, a bit complicated, but not all that hard to understand.

Its much simpler if one looks at from the perspective of the Enterprise-C: in the middle of a battle, when they get sucked into a Bad Future, one which hinged on their disappearance mid-battle. The future folks help repair their ship, then send them back in time to avert the bad timeline in favor of one they all hope will be better.

"In The Beginning," established that while time travelers can make small changes, they will ultimately lead to the same result because destiny cannot be changed. This is ultimately proven true when Dean's attempt to protect his family from the Yellow-Eyed Demon ends up causing his mother to make the deal with him that eventually kills her.

There is a bit of confusion after Dean convinces his father, John, to buy the Impala Dean himself will eventually inherit instead of the VW Bug John had initially intended to buy to impress girlfriend Mary, Dean's eventual mother. Would John have bought the VW Bug if Dean had not interrupted with his suggestion?

"My Heart Will Go On" blatantly contradicts this by having an angel go back in time and stop the Titanic from ever sinking, preventing anyone on board from dying and leading to hundreds of their descendents who originally never existed appearing in the present. However, the angel who un-sinks the Titanic also states that ever since the Apocalypse was averted, the old rules no longer apply (presumably because the Celestial Bureaucracy is in disarray and can't afford to be watching over every minute detail in order to ensure that it all leads up to its supposed "destiny" anymore.)

Much like in "In the Beginning", "The Vessel" presents a confusing question as to whether history stayed the same in spite of Dean's presence, or if Dean's presence inspired the events that become history as he knows it. The boat is sunk by the use of the Hand of God to sink the German sub, but the crew didn't know about the sub or the Hand of God until Dean made them aware of them.

While each Terminator movie managed to be internally consistent, Terminator: The Sarah Connor Chronicles combined the continuities of the first two movies and then added some of its own time travel plotlines. Predictably, it's getting a little weird.

The episode "Complications" is particularly troublesome. It introduces a new stable time loop and strongly implies that Derek and Jesse don't come from the same version of the future.

Later in the series, there's so much timeline alteration going on the human time travelers start using the ever-shifting date of Judgment Day to determine which timeline they came from.

There's also the terminator that was sent to the wrong year and ended up having to build a building. Things get complicated when you try and work out how such an early intrusion into the timestream plays out with all the time-travel shenanigans already going on. Being a new model terminator at the earliest point in time raises many questions. Did that one with new orders cause the current events? Would it still arrive in the past if that chain of events were excised?

Time Trax can't seem to decide if Darien and the fugitives are in their own past or a time-shifted parallel universe. Most episodes appear to take the second option, insisting that their own time remains unchanged no matter what happens in the "past". On the other hand, in some episodes, Darien has SELMA leave coded messages in the classifieds for his boss in the 22nd century, which would only be possible in the first version. No one seems concerned about any temporal paradoxes, though, and Darien's goal is not to prevent any changes but to catch escaped criminals. One episode is notable for having both versions: Darien insists that, due to everything that has already been altered by the time travelers, an aspiring country singer may no longer become the star she was in his own history. At the same time, he accidentally becomes the inspiration for his favorite song.

Timeless for the most part appears to be fairly established in its time-travel rules. It is possible to change the past, though the result is usually a Close Enough Timeline. And yet, the Butterfly Effect is a very real danger, except when it comes to big historical events (a case in point - the protagonist's sister is inadvertently erased from existence because of small changes to a particular historical event, but the premature death of as important a historical figure as Lord Cornwallis doesn't completely change American history. Ripple Effect-Proof Memory applies to time-travelers, but there is no Ripple Effect Indicator - objects that are taken to the past in the machine retain their original state irrespective of changes to the timeline. The major contradiction though is despite all this, the series seems to be getting up a Stable Time Loop - one of the main antagonist's is motivated to try to change history based on a journal he received from the protagonist's future self describing some of the events of the series!

Timeslip, a 1970s British series, presented a form of time travel where the past, not "really" being able to "happen again" is "fixed" — by which they mean that you can interact with the people there, but not alter events, and can be hurt, but not "seriously". In the first serial, a time traveler is shot dead, and collapses, unconscious, leaving blood, but no wound. She wakes up, but still feels the pain of having been shot. You get the first minute of a muddled explanation about it being a sort of shared hallucination before it's dismissed as too complicated to explain.

For its first 3 seasons Eureka is nice and consistent that any mucking around with the fabric of time is catastrophic, then season 4 came and dropped the ball. Pilot: using a "tachyon accelerator" to accelerate a particle beyond the speed of light uses a "tachyon collision" that will destroy the town, if not more. Season 1 finale:Mental Time Travel creates an alternate timeline, but the "real" timeline starts to bleed through and destroying both timelines; necessitating time travel again to Make Wrong What Once Went Right. Season 3: slowing a single photon down causes a "Groundhog Day" Loop and if it's not sped back up and the loop broken the town, or more, will be "erased from existence". Season 4: Using a wormhole to travel to the past changes the current timeline, there is no threat of collapse or erasure outside 1 episode which makes it due to "exotic particles quantumly linked across time", the time travelers replace their counterparts when they return to their time yet maintain their memories of the unaltered timeline, and then 2 of them travel to the past again and witness their first visit without changing anything else or creating any more problems (or even replacing themselves in the past from their first visit to the past - or in the case of 1 traveler, he was originally from the past and didn't replace his original past self).

This is a fundamental quality of Warp travel given that the flow of time relative to realspace changes randomly during transit. Navigation for The Imperium of Mankind requires the use of psychic Navigators to essentially feel their way to their destination, avoiding the worst of the warp storms and riding favourable currents to reach their destination. However, given the abovementioned mutability of time along the way, when you arrive is anyone's guess. The crew could be in transit for weeks or months at a time to arrive at their destination at the same time as when they left, centuries late, or even before they set out, if you even get there at all. A graphical history for a given ship would more closely resemble a circuit diagram than a timeline if plotted out.

One specific example had an Ork leader accidentally end up at his starting location just before the fleet left, and then promptly attacked and killed his past self to get a spare of his favorite gun (the Waaagh! disbanded in the ensuing confusion).

There is also a long-running war between Eldar Farseers (who can manipulate current events to change the future) and actual time travelers from the Necron dynasties and Imperial Inquisition (who may or may not have accidentally erased themselves from the timeline).

One Imperial ship responded to a distress signal, but was ambushed in the Warp. Just before its destruction it managed to send out a distress signal...

Completely averted in the indie RTS Achron. The time travel is completely consistent, despite the game handing the players tools to: change the rate time flows around them, give orders to units in the past, send units into the past using time travel, and create time paradoxes... in competitive multiplayer. Bonus points for the system still managing to be fairly easy to learn.

Apollo Justice: Ace Attorney manages the difficult trick of pulling this off in a game that doesn't feature time travel. In the last episode, Phoenix's investigation as shown would not be possible unless he could actually travel through time, rather than being able to select different times just being a tool for the convenience of the Jury. He uses evidence he gathers in the present in the past, as well as evidence he gathers later in the same portion of the timeline in earlier incidents. Justified in that the Investigation you see is a simulated version being played out by the Jurists.

Back to the Future: The Game confuses the series' time travel mechanics even further, when Marty and Doc inadvertently create a timeline where Emmett Brown never creates the time machine in the first place (and in fact never becomes "Doc" Brown). While Marty is unaffected by the changes in the timeline (so long as it doesn't result in his erasure from existence, as usual), Doc actually disappears from the DeLorean once they land in 1985. The DeLorean doesn't start to disappear until Marty managed to get the 1931 timeline mostly straightened out, but only after another Doc Brown travelled back from 1986 to pick up Marty, and it took days for the thing to finally vanish.

Deconstructed in Bastion. The narrator gets several serious cases of deja vu retelling the story of The Kid to his audience, and one of the game's endings directly lead into the beginning of New Game+.

To say that this trope pops up in BioShock Infinite is like saying there's some water in the Atlantic Ocean. So you're hired to retrieve a girl from a floating city run by a racist madman who believes himself to be the American Jesus. Seems simple enough. Then you find out the girl can rend spacetime, go on trips to multiple time lines, find out the girl is the daughter you sold away in one possible world, and that the bad guy is a possible you.

While Chrono Trigger was generally consistent about how its time travel worked, there were a few odd instances.

Somehow Marle paradoxed herself out of existence, despite time travelers not being directly affected by any other changes they'd made during the game. For instance, you can save Lucca's mom, but Lucca still remembers when she was crippled instead of having all her memories changed. Or when the future Robo came from was erased from existence without affecting him.

For Lucca, it's uncertain if she remembers her mother being paraplegic. After saving her and returning to the present, you can visit her and see she walking, but nobody (not even Lucca herself) comments on this.

The Timey-Wimey Ball also applies to game mechanics: One can open a chest in the future, return to the past and open the chest again to get two items from the same chest.

This also means that it is possible to beat the optional dungeon at the end of the game 3 times. However, if you start by beating the earliest version of it the newer versions will also be empty.

According to the staff members, they never quite got a consistent set of rules down for time travel until they had already written themselves into a corner, so they just went with what they had.

Chrono Cross tries to patch things up by using parallel realities as the ultimate outcome of fiddling about with temporal mechanics, and then showing the physical effect of a catastrophic temporal paradox via the Time Crash (wherein a time experiment pulled a city borne from the "good" future back to the past, and its opposite number from another alternate reality was ripped from its native timeline as cosmic counterbalance; the "time refugees" created the archipelago the game takes place in, and ultimately things happened leading to an alternate reality where the "bad" future is still set to occur.)

The Command & Conquer: Red Alert Series - seriously, the series by now has something in the range of 2 separate timelines from the first game, two from the second, two from that game's expansion, and then three from the third game, with a further three paths from THAT game's expansion. Even more brain-busting, Red Alert led to Tiberian Dawn by way of Allies winning both Red Alert 1 and 2 - Red Alert 3 is made by way as a divergence at the end of Red Alert 2. Add to that the events of Yuri's Revenge which is its own separate divergence and has the nice consequence of there being two "commanders" (the player) in different places at the same point in the timeline, although the divergent timelines are merged at the end.

Dark Souls: The Player Character is told from the beginning that time in Lordran is inconsistent; everyone has their own "world" (i.e. timeline) wherein their own pasts and futures proceed in the standard way, but each of these worlds is technically separate from every other. Occasionally, two or more worlds can overlap temporarily and their inhabitants interact. The catalysts vary - people can leave messages for one another, including "Summoning Signs" that allow other travelers to request their aid, while other times these overlaps just occur naturally. Alternatively, certain "Orb" items can be used by players to invade other worlds to kill the hosts.

Dark Souls III takes it Up to 11: not only is the previous "each player has their own timeline" mechanic still in effect, but the realm of Lothric has absorbed elements of other realms of the past as a side effect of the resurrection of the Lords of Cinder. This includes having Anor Londo appear in a place that makes absolutely zero sense for it to appear in. The Untended Graves and the Dark Firelink Shrine therein are alternately suggested to be in the present, past, or a possible future in different ways. Then there's the Dreg Heap, a giant amalgamation of rubble from all eras just haphazardly piled up on top of each other, which might be in the distant future or it might be an alternate plane of reality. The Ringed City DLC also introduces the Plain of Ash, which is suggested to be the ultimate far future in which the end of the world is happening... or it might be what the world actually looks like now, with everything else being an illusion?

Day of the Tentacle, is extremely wibbly-wobbly timey-wimey. The game runs on San Dimas Time to allow the characters to flush small, inanimate objects to each other through time via their time machines. When the time stream is altered, any changes are visible to the characters and happen with a "magic" effect and sound, and at the end of the game, the characters travel back in time to yesterday to turn off the machine that caused the Big Bad to become evil, thus causing a huge paradox and defeating the point of them even disembarking on their adventure in the first place. But that's okay. Doctor Edison's original plan (not taking into account the diamond breaking and the trio ending up in different eras) was for them to simply go back in time and turn off the aforementioned machine.

Dragon Quest V has a literal Timey-Wimey Ball. As a child, your character finds a golden orb which doesn't seem too important. A bit later, you meet a stranger who asks you if he can have a look at it. At one point, the leader of an evil cult destroys the orb for no apparent reason at the time. After a timeskip and many hours of gameplay, your character, now an adult, finds out that the golden orb was really the power source of a floating castle. You then receive a fake golden orb, go back to the time of your childhood through a magic painting and secretly exchange the orbs with your younger self and return to the present with the real one, meaning that the cult leader only destroyed the fake.

Dragon Quest VII takes it Up to 11 by centering the entire game around traveling to different times and places in order to restore the world... Good luck with keeping the different time lines straight.

The activation of the god-golem Numidium in the conclusion of The Elder Scrolls II: Daggerfall allowed for several mutually-exclusive endings. The story-writers decided the simplest answer to this situation was for all of them to be true; the lore-writers followed suit. Cue the Dragonbreak, a moment in history where the Numidium's activation was so powerful it broke time. Time followed every possible path the player could follow, each time ending with Numidium's destruction... and then time snapped back together and every event became part of the new reality.

This has resulted in interesting paradoxes, including the existence of both the Worm God and Worm King, when they are both Mannimarco and should only be one or the other.

Generally, Dragon Breaks are closely related to the lore's concept of "Hero" (all Player Characters in the series are considered Heroes), an individual that is Immune to Fate, which allows the world's fate to continue despite the myriad ways the Hero can affect the game world (often in contradictory ways in different playthroughs).

One puzzle involves a time-travel maze where, at one point, you encounter your future self (and, later on, your past self, in exactly the same situation only controlling the other Guybrush). Taking an incorrect course of action (usually saying something wrong as the future self) creates a "paradox" that throws you back to the start of the maze. The puzzle goes a long way towards demonstrating the problems with a Stable Time Loop.

There's also the three items you get from your future self, and have to give to your past self. Where do they come from? Where do they go?

Despite only reading about the past rather than visiting it, Eternal Darkness uses a rather... unconventional form of this in the ending of the third play-through. Near the start of the first one, you picked one of three artifacts which would end up being the Big Bad. In the second play-through, that artifact was gone and you picked from the remainder; the ending was basically the same as if you had picked THAT artifact first, but the voice-over states that "something seems to remain". The third one was the same, leaving a single option; the third ending shows that all three events happened simultaneously, and were in fact the only way for Mantorok - the only even quasi-good member of a pantheon of four godlike beings that exist outside of time and space - to destroy his hideously evil counterparts. This opens up the New Game+ and allows for very satisfying cheats, but the ending in this final "joined together" timeline states that Mantorok itself is still sealed, rotting, scheming...

Final Fantasy XIII-2 has a case of this once you get into the multiple time-streams. One specific example is that a solution to being trapped in an insane building by a computer trying to kill you is to scream at Hope, who is in the original timeline in the distant past and will see the video and not create the insane computer.

Fire Emblem Awakening has some minor, weird cases of this. Midway through the game, you can start recruiting the main cast's future children, who all time-traveled to the point of the main quest. However, one of them ended up three years earlier than the rest of them for completely unexplained reasons, technically making him the oldest of the bunch. Plus, Morgan, the Avatar's exclusive child, is speculated to have come from a different timeline than the rest, which would have to be the case with some of the possible pairings (particularly if the Avatar marries a 2nd-gen character). To add to the confusion, various dialogues and DLCs (particularly "The Future Past") imply all of the above-mentioned time-travelers would be more accurately described as Dimensional Travelers.

Legacy of Kain. Time-travel, paradoxes, Decoy Getaways, and so much more! It would take an entire page on its own to list everything... but you can always see for yourself at the other wiki.

The Spirit Temple in the OoTMaster Quest has a switch only accessible in the future that drops a chest only accessible in the past.

Then there's the Song Of Storms. Link learns to play it on his ocarina from the Windmill Guy, who's ticked because "some Ocarina kid" came 7 years ago and played it, messing up the windmill. Guessed who the Ocarina kid is? And how he learned the song? That's right, from Windmill Guy, 7 years in the future. Of course, by itself a mere ontological paradox isn't enough to claim this trope - it is after all a very common hazard of Stable Time Loops - but when you combine it with the timeline split...

This is repeated in The Legend of Zelda: Oracles of Ages, during a Chain of Deals no less. The one link involves getting an antique vase from one Goron in the present, who claims it's a cherished family heirloom passed down through generations. Your next link is to give it to his ancestor 400 years in the past, who promises to cherish it and pass it on to his children. ...Just let that one go.

The Legend of Zelda: Majora's Mask is even worse about this. Link is stuck in a "Groundhog Day" Loop that lasts for three days. Whenever the loop starts over, his actions in the previous loop are erased. There are no time travel duplicates, which erases the possibility of another Link running around doing things you've previously done. Instead, they simply don't occur unless you go and do them again. Despite this, once you defeat the final boss, all the cycles you've completed are somehow merged together without explanation and everyone is saved, rather than just the people you helped in the final cycle. Even if you speedrun this doesn't make any sense since the game cannot be fully completed in a single cycle (one sidequest in particular has to be done at least twice in two different cycles with slight variations for 100% Completion). This was probably just done so that the game could have a happy ending, but it seems to break the game's own rules about how Time Travel works. Maybe the Goddess of Time did it.

When you travel back in time, Link loses all his consumables (rupees, arrows, potions etc.) but keeps all the gear he has acquired and can even regain certain things if he's lost them (like if Takkuri steals your sword). This doesn't make much sense no matter how you slice it, i.e. if Link is physically traveling back in time then he should take everything with him, but if he's performing some sort of Mental Time Travel then he should take nothing with him.

In four games, the precise nature of time has never remained constant. Ocarina of Time contains at least two very different mechanics, which theorists often find irreconcilable (and downright strange). Ages mechanics only begin to make sense when one sacrifices logic to storyline completely, and Majora's Mask's Goddess of Time takes the whole thing to hell by drawing questions of omnipotence into the debate.

—The Internet, Trying to solve the mess that is the Zelda Timeline.

Even the map is not consistent: most of the time, there is a ripple effect/timeline alteration, but some instances are only plausible with a Stable Time Loop, such as a dungeon that gets opened with a special object in the past and that, in the present, becomes another dungeon, visited earlier in the game.

The Legend of Zelda: Skyward Sword continues the tradition with Timeshift Stones. When hit, they revert the area around them to several hundred years in the past. Oddly, however, any change you make in the present near one of these stones will still be there in the past. And then, near the end of the game, Link uses the Triforce to kill Greater-Scope Villain Demise in the present. However, Ghirahim kidnaps Zelda and uses her to free Demise several centuries in the past. Link follows him back and seals the past Demise within the Master Sword, which he leaves in the past Sealed Temple. None of this is shown to have had any effect on the timeline when Link, Groose and Zelda return to the present in the ending. The funny thing is this could have worked as a Stable Time Loop had they trapped Demise in the Sealed Temple again instead of in the Master Sword.

Even weirder is that the first time you visit the Sealed Temple, you can see the crystal Zelda eventually seals herself inside which is created later in the game, but in the past. The Master Sword, however, doesn't appear until the end of the game, even though that also happens in the past. Also, near the end of the game you gain the ability to travel between the past and present at will. You can do this without consequence, even though Demise has been freed in the past and would presumably have wrecked havoc on Hyrule and Skyloft without Link to stop him. He does say he would give Link time to prepare before their final battle, but you'd think after several hundred years he'd have gotten tired of waiting.

Time travel is central to the premise of Millennia Altered Destinies. The Player Character is a human recruited by a mysterious alien race known only as the Hoods to alter the history of the Echelon Galaxy to prevent the hostile Microid race from conquering it. With the XTM ship, the player is able to perform space/time jumps around Echelon and make certain changes to ensure the successful rise of four alien races, so they end up resisting the Microids and provide you with the replacement for the parts for the intergalactic drive to return home. The XTM has Ripple Effect-Proof Memory, so the changes don't affect you, except for the historical database specifically designed to avert this (so you can see what's been changed). One of your enemies are the Hoods themselves, who have previously attempted to make changes to the galaxy's past. Your greatest enemy is your Evil Counterpart, an alternate version of you recruited by the Microids to ensure their dominance. Like you, he has his own XTM, is immune to timeline changes, and can travel to any planet in any time period, ruining your hard work. It's the only part of the game that runs on San Dimas Time. Additionally, if you arrive to the time period he screws up, you can chase him off before he can do the damage, but the timeline will not necessarily be restored to what it was (even though it should). Also, the game is not very consistent as to your communications with your agents on the four races' homeworlds. Sometimes, the agent will react to your second call as a follow-up, while other times, he will react as if it's the first time you're calling him in this time period, allowing you to make a different choice from before. The game originally had a Non-Standard Game Over happen if you manage to screw up the timeline so much that you can't undo the changes (via an extremely powerful time ripple that destroys your XTM), but then they realized that this can never happen in a game about time travel and removed the option.

In Minty Fresh Adventure, Colgate can encounter Derpy, who's trying to deliver a letter to her, and the Doctor, who wants Colgate to not read said letter. The letter is Minuette's application for the position as a dentistry receptionist, from six months into the future, thus suggesting that Colgate will succeed in her quest to become a dentist. There are four endings depending which encounters you do; if you meet both, the Doctor will happily chide Derpy for nearly destroying all space and time just to give Colgate a little motivation.

There's No Time to Explain how time travel works before your future self gets grabbed by a monster and you have to go chasing after them.

Ōkami manages this. First of all, you travel back in time to defeat Orochi with the help of Shiranui, your past self at full power, your grandfather, or yourself later in the game depending on your view of the Space Time Continuum. Next, Shiranui comes forward in time to help you beat the first part of the boss fight, only to get mortally injured in the present, then going back in time to die. Then, Chibiterasu, a son of Ammy, goes back in time to help his mom beat Orochi from nine months ago, thawing out his grandfather/mother at full power then going back in time 100 years in the past and... Yeah.

The Prince of Persia Sands trilogy is one massive example of timey-wimey craziness.

At the end of The Sands of Time, the Prince entirely reverses the events that just took place, making it so the events of the first game don't happen. This seems to have created a paradox by the start of the second game.

In Warrior Within the Prince is being chased by the Dahaka in the present, a timeline guardian who is trying to ensure that the timeline proceeds as it was meant to. He is not chased in the past. The Prince inadvertently creates a Stable Time Loop when he kills Kaileena and creates the Sands of Time, the very thing that he was traveling back in time to prevent, discovering that he has already changed the past, just as he was fated to do! At this point, he then is chased in the past as well, as he still needs to be killed for unleashing the sands. Then, he discovers a way to co-exist with himself in the same timeline, which he uses until his normal self in the past timeline is killed, allowing him to remove the Mask of the Wraith. He then returns to the past to attempt to actually change his fate.

At the end of the second game, in the Golden Ending, he has killed the Dahaka and successfully prevented the Sands of Time from ever being created, causing a true disruption of the timeline.

In The Two Thrones, the Prince discovers that his paradoxical actions in Warrior Within mean that the Vizier was never killed and war has been unleashed on his homeland. The Vizier captures and kills Kaileena, once again unleashing the Sands of Time and effectively repeating the events of the first game in a different setting. The Prince eventually kills the Vizier seals away the Sands again and seems to have learned from all his futile time-travel, as he leaves the end of the game be with no further meddling, happy with the one actual change in his life that he actually got to stick, Farah's survival.

Radiant Historia is all about using this trope, Tricked Out Time, and most other Time Travel Tropes in a quest to ensure the Golden Ending. The most confusing aspect is that while there are two separate timelines, making changes in one somehow influences the other, leading to things like helping someone recover from severe depression in one timeline so he won't try to kill you in the other one.

Episode 204 of Sam & Max, "Chariot of the Dogs", focuses on Time Travel. This is Sam and Max; any time travel plot WILL bring in to play every time travel concept as fast as it can for the parody.

Several stable time loops are created, including one that is required for getting Sam and Max to the time machine in the first place and another that comes into play in episode 205. However, as if completely ignoring the idea of stable time loops, much of the puzzle solving revolves around completely altering the time stream just so that you can fix a problem created by Max's personality the moment you start time travelling.

One section even has Sam and Max accidentally letting themselves from the first season take their time machine, effectively rewriting everything the player had done in the past year, AFTER a needed macguffin to advance the plot was taken out of the time stream.

Second Sight plays with the trope. When John Vattic finds his way to the records room to find Jayne dead, he seems to flash back to the point when she is supposed to have died to save her, eliminating the reason he flashed back at all. This happens a few times in the game, to the point of Mind Screw. However, what's really happening is that the "past" the player is experiencing is, in fact, the present, and the "present" is a premonition caused by the protagonist's latent psychic powers emerging. It's pulled off extremely well.

Shadow Hearts: Covenant: A Timey-Wimey Ball in the good ending sends the main character back to the beginning of the first game with the implication that both of the first game's endings are canon. It also sent Karin back in time to meet Yuri's father and become Yuri's mother.

Even that's not correct anymore, because Sonic Generations centers around the Time Eater, a creature that can take places out of time. One of the places he takes, is Crisis City, the Bad Future version of 06's world. Even though, 06 never technically happened and shouldn't feasibly exist for the Time Eater to be able to access the events that happened in it, it somehow does, meaning that '06 does exist, but doesn't exist, simultaneously. Also, you play Crisis City where '06 fits in the timeline, not adjusting for the fact that Crisis City technically comes from a future that presumably took place well after the events of Unleashed and Colors. Fair enough, since Sonic first visited Crisis City in that order, but it still adds another layer of Timey-Wimey to everything.

Tactics Ogre, despite its Chariot and Wheel of Fortune Tarots, averts this entirely. Although the World Tarot lets you relive the other chapter paths, thus opening up the possibility for a Timey-Wimey Ball, the final events in Coda suggest that this is not time travel, but merely Denam's imagination.

In Tales Of Majeyal this is how unlocking the Chronomancer classes works. When exploring the Daikara mountain range you can enter a Temporal Rift optional dungeon, which consists of alternate versions of other areas populated by weird extra-temporal monsters. Defeating the bosses unlocks the Temporal Warden class for future games. When you enter the Daikara when playing as a Temporal Warden you are attacked and killed by your future self. The Grandfather Paradox then kills your future self, un-kills you, creates the Temporal Rift, and unlocks the Paradox Mage class.

The Talos Principle: Shepherd, being trapped in the Tower outside the normal bounds of the simulation, is somehow able to communicate with previous generations and give them advice.

The Obvious Beta action-adventure game The Time Machine runs into a more literal version of this. Time is like a flat plane in the setting, and by travelling to the future, Wales causes his time and the future to become tied together by the time machine itself, pulling time together into a whirlpool of sorts that starts destroying time as he knows it. Which makes absolutely no physical sense, but serves to explain why returning to his previous time(and thus putting himself and the Time Machine back in the time where they belong) prevents any further damage to the time plane.

TimeSplitters: Future Perfect relied on Stable Time Loops for plot progression; for example, early on in the game Cortez receives a key after holding a conversation with himself through a grate in the ceiling ... then later, holds a conversation with himself through a grate in the floor and drops himself the key. And then in the game's conclusion, Cortez changes the past, stopping the Time Splitters from ever being created, complete with his Present being changed from a ruined battlefield to a beautiful landscape, with no real effect on him, or anyone else from his time. This utter disregard for consistency is all worth it for the scene where Cortez is stuck in a vault with security systems trying to kill him, which the player plays through several times, thanks to the Stable Time Loops, and even gives himself the password, seemingly picking it out of thin air.

Ultima I has you stop the evil and immortal wizard Mondain by travelling back in time and defeating him before he became immortal. Doing so should remove the centuries of tyranny and oppression from history, as well as cause a grandfather paradox (why would you go back to defeat Mondain if he was already defeated long ago?), yet everyone remembers everything.

Ingame, this is the home of the Bronze Dragonflight, Guardians of Time, which need the players' help against the Infinite Dragonflight which are trying to mess up the timeline. But really, it's just an excuse to let players reexperience some of the key moments in Warcraft history, although in a different way (instead of Thrall escaping captivity with the help of a human girl causing distractions, the players need to bail him out by force). If you screw up, the Bronze Dragons just hit the Reset Button until you get it right. The Doctor may have used the TARDIS for sightseeing, but the Bronze Dragonflight runs a travel agency.

And in patch 4.3, players get to travel back again, via the Caverns of Time, to the events in the War of the Ancients, to retrieve a magical artifact. However, the events of another novel are centered around said artifact, meaning they logically would be retconned. Given that the events of that novel are what indirectly led to the rise of Deathwing, who is the main reason for recovering the artifact in the first place ... confusing doesn't even begin to describe it.

The existence of Murozond is one big example. At some unspecified point in the future, Nozdormu, Dragon Aspect of Time, will go insane and become Murozond, who creates the Infinite Dragonflight and wrecks havoc on the timeline with the goal of bringing about a Bad Future. Nozdormu himself is aware of this. He is also aware that this will lead to his death and that Murozond will ultimately fail to change anything, having both been granted a vision of his death by the Titans and personally witnessing it happen to his future self in the End Time. Murozond's dialogue in End Time implies he is indeed the same Nozdormu we interact with in the present day, and not an Alternate Timeline version of him, as he berates his younger self for "not know[ing]" his reasoning back then. Yet somehow, he still seems certain enough he will succeed to try and change the timeline anyway. But then Nozdormu loses his Aspect Powers in the Dragon Soul raid, which takes place after we're sent to the End Time but before Nozdormu becomes Murozond. Murozond does not seem to be weakened by this in End Time. Despite all this, Nozdormu is certain he will eventually become Murozond and there is nothing that can be done to stop it... Even though all he'd need to do to prevent it is not attempt to change something he already knows he'll fail to change if he tries.

Murozond was taken down by a 5-man group with some assistance from his past self. Malygos and Deathwing, meanwhile, required 25-man raid groups plus extensive backup. It's safe to say that Murozond was weakened by the whole depowering thing. Additionally, Nozdormu was told by the Titans that he must not change the circumstances of his death under any circumstances, so simply not doing anything that could turn him into Murozond is unacceptable.

Warlords of Draenor, the expansion pack announced at Blizz Con 2013, takes place in a Draenor heavily affected by the Timey-Wimey Ball. Garrosh escapes from prison, flees into the past of Draenor, stops the Orcs from drinking Mannoroth's blood, and introduces modern technology, creating a new "Iron Horde", changing the destiny of every major player on Draenor (and even the world itself). The only change to modern Azeroth, however, is that the Dark Portal changes from Green to Red, linking to the new Draenor, not Outland. How Azeroth is completely unaffected is thus far, unexplained (though one can assume Twisting Nether Timey-Wimey stuff.)

Word of God is that Garrosh traveled to a different timeline altogether.

Life Is Strange is pretty good about their internal rules. Max can rewind a short time (At most a few minutes) while she remembers what happened before, this is the 'first' time for everyone else. (This allows her to use 'future' conversations in the 'present.' This is also how she can change decisions in one area, but as soon as she leaves, she can't. It's too far to rewind.) However once you move beyond those rules, it starts getting confusing. Starting with how she freezes time once without explanation and never done again. Time Travel through photographs is completely unexplained. As is the fact that she is 'replacing' her double from that timeline. (though she keeps the memories of 'her' timeline) and she somehow had a vision of the tornado at the end of the game before she got her powers. And one of the two endings heavily implies she wasn't supposed to have the powers in the first place. In fact, several characters theorize that her powers CAUSED the tornado. Despite how she saw the Tornado BEFORE she got the powers, and her powers activated by accident trying to save someone's life. The ending is divisive.

In Destiny, time travel happens but the exact nature of it is... iffy. The Vex superintelligence seems to greatly enjoy the benefits of time travel, being able to casually traverse various timelines, pulling units, materials, and even energy from different points in spacetime, to the point that their basic weapons yank points of energy from other random parts of time and space. They even have the ability to retroactively control spacetime and decide if something exists.... or if it ever existed in the first place in certain locations. Other pieces of Vex technology include machines that allow users to actually travel through time, seeing the future or viewing alternate timelines. On the other hand, the Traveler and the Guardians seem to be distinct in their ability to ignore changes in timelines and reality-alteration, to the point that the Guardians are able to outright deny temporal changes within the Vex Vault of Glass using their Light.

God help anyone trying to understand the way time travel works in The 3rd Birthday - though it's likely that most of the problems were caused by the game's Troubled Production and far from final script draft. Sometimes, changing the past causes complicated butterfly effects that leave to other characters being alive. Other times, it causes people to become paradoxed out of existence, Back to the Future-style. Other times it causes people to become temporal ghosts unable to interact with normal events. Whether other characters can remember previous timelines seems essentially random.

Visual Novels

Time Hollow suffers from this trope at times. At one point, you rescue a mother and son from dying in a bus crash. Immediately afterwards, time refuses to change. So you try again. And again, nothing happens. Turns out the mother deliberately RE-changed events to cause her and her son's death. This is handwaved with an explanation that objects and people pulled or otherwise sent through a time warp become 'detached' in time. It may make your head hurt a bit more when you are able to talk to the mother, older, in the timeline in which you saved her, even though that timeline, from your perspective, DOES NOT EXIST because she keeps changing the past to prevent it.

Virtue's Last Reward requires Sigma to betray Phi at a critical juncture in order to open a plot lock. Due to this being an incredibly ridiculous and out-of-character thing to do, it is highly likely the player will only try it after Phi betrays Sigma in the alternate branch where Sigma allied — which she explicitly declares she's doing only because of Sigma's betrayal in the other path. You could almost call this a Stable Time Loop, except that it's an interaction between two different alternate universes that can only connect through Phi and Sigma's Time Travel powers.

Web Animation

Red vs. Blue starts out with a Stable Time Loop when Church keeps going back in time and ends up causing almost every problem that happened to the Blue Team. Then in season five, Wyoming uses his time travel ability (which Church was originally using without knowing it) to try and win the battle. Tucker has Ripple Effect-Proof Memory thanks to his sword and they end up doing things, and then undoing them. For example, Caboose is killed by the tank, and Tex gets knocked out/killed by Wyoming. In the "final draft" of the timeline, Tucker yells at Caboose to stay away, and warns Tex that Wyoming knows that she's there. Then it turns back into Stable Time Loop when Caboose's mental image of Sister, who is a guy, gets pulled into the real world. S/he ends up materializing next to a dead Wyoming, whose suit malfunctions, sending him all the way back to Sidewinder. Turns out, he was the mysterious "Yellow Church" that fans speculated about for years.

Since the "Yellow Church" claimed his plan to solve the Sidewinder crisis "seemed like such a good idea at the time", it could be safe to speculate Sister/Yellow Church is there due to a further loop leading back to Sidewinder.

The series later attempts to explain all this earlier time-travel nonsense during the "Recollections" trilogy of seasons by explaining that the Red and Blue soldiers are actually simulation troopers meant to test Freelancer troops against a myriad of mad situations and everything they were subjected to in Blood Gulch was in fact a controlled situation they weren't meant to understand.

Actually Word of God from Burnie Burns has confirmed that Church going back in time repeatedly never really happened, and was merely Gamma and Omega trying to cause Alpha to fracture into more A.I. fragments. Nobody moved through time in season 3. Yes this is a major retcon, but as of Season 8 it is considered the canonical explanation.

Web Comics

Used to great effect in The 10 Doctors. It's even mentioned by name as to how all ten Doctors can be in one place at the same time.

In Bob and George most of the characters can never find out what kind of rule Time Travel goes by, and one person once said it can be changed by the setting on the time machine. However, it appears that they follow Stable Time Loop rules, as no time period is ever affected by what happens in another. Indeed, the only way time travel is different than going to a different dimension is that people think it may change history.

Dr. Light's lab is clearly shown being pre-destroyed by a time ripple tearing through it and enforcing events from the new past. So yes, the past can be changed if you use the time machine right.

The ending however, suggest a stable time-loop, as it ends with a suggestion from a time-travelling ghost of Zero telling Wily to not activate him so he won't kill everyone. Then they all fake their death and move to Acapulco to prevent a temporal paradox.

There is a very good reason why "I hate Time Travel," is one of the more common Catch Phrases of the comic.

At another point, Protoman adds a fresh level of murk due to a) lacking Ripple Effect-Proof Memory and b) being paranoid enough to know he lacks Ripple Effect-Proof Memory, by remarking that a time-travel story is exactly how he remembered the events in question...well, it's how he remembers it now.

The sequel fic Forever Janette intentionally invokes the Timey-Wimey Ball by subverting the show's use of San Dimas Time — by letting the Fifth Doctor meet the Master from the Seventh Doctor's time. It doesn't say how this is possible, other than a passing mention that the two Time Lords are "off-phase" from a common Gallifreyan synchronicity.

Time travel in Irregular Webcomic! at first appears to work in a Stable Time Loop fashion, but then it's revealed that It's possible to "break" a Stable Time Loop, an action capable of destroying the entire universe.Several time loops have already been broken. And now Every universe, save the "espionage" theme universe, has been destroyed. They got better. And now apparently the timeline is too broken to go back pre-1933 (specifically the date of the Reichstag Fire). Complete with a link to this very article.

Looking for Group has a big fat temporal loop in the Kethenecia arc in Book 3, but really the arc underlies the whole story so far. It's still uncertain if the protagonists can actually change the timeline should they chose to, since so far they did their best to fulfill the prophecies.

It's openly stated by a member of the Time Police in L's Empire that all bets are off if you time travel via magic.

An extended time-travel subplot establishes that it is difficult, but not impossible, to change your own history. Physical time-travel takes all the energy that exists in the Universe or, as it turns out, in some other universe that's just out of luck, but it's possible to transfer your consciousness back or forward in time into your own body, and you can undergo changes as a result of altered behavior. For instance, Dave never smoked. At several points, the question of paradoxes comes up, and it is immediately dismissed by pointing out that thinking about it could cause it to happen, so it's better not to.

The same storyline provides an example of inconsistent time travel effects within a single sub-plot. Dave didn't cease to have ever smoked until after the time travel; however, Caliban's demotion, though also caused by the time travel, was established backstory before the time travel occurred.

This page of the Midnight Crew intermission in Homestuck typifies the response. Though most of the time travel shenanigans seem fairly self-consistent, it's still hella complex.

In the main continuity of the series, it gets worse when Future!Dave starts incorporating Time Travel shenanigans. And even he doesn't understand all the mechanisms behind it, his advice to the other characters (and the audience) is just basically "Don't overthink it."

Dave: see the thing with time travel is Dave: you cant overthink it Dave: you just got to roll with it and see what happens Dave: and above all try not to do anything retarded John: i'm just the timey-wimey messenger here.

However, Magic A Is Magic A applies heavily and every form of time travel is internally consistent. The problem arises when there are at least four different forms of time travel, and possibly even more, all of which abide different rules

Heroes of Time have two options. Either A) They change destiny and cause a branch timeline, or B) You Already Changed the Past. They naturally have some intuition about what changes cause what. Time magic practiced by the Felt is more loose, and can be used for pretty much any form of Time Travel. And then there's the weird stuff, like the Furthest Ring distorting space and time, potentially causing someone to meet their past selves by traveling in a straight line and Skaian portals.

This is probably gonna be the only way to understand the whole time traveling bit in Sonichu. To wit, Author Avatar Chris is launched into the future where he is able to help those in the future make the vaccine for homosexuality (even if that's not how it works) before being able to convince his future wife Lovely Weather he is his future self (despite the fact that he'd be ten or so years older) and do the nasty. He comes back, gives Magi-Chan Sonichu a Sonichu Ball and tells him to go back and get some of the vaccine to bring back to the past so they can cure everyone years earlier. And while he does talk to the past version of Lovely Weather, there's the case of the vaccine - if he brought the vaccine back from the past to cure everyone, why would there be a need for it in the future and oh, going cross-eyed.

There don't seem to be any concrete rules to Sluggy FreelanceTime Travel. Possibly justified by the presence of beings like Father Time, Uncle Time, and the Fate Spiders who have an interest in making sure time runs smoothly and/or in a fun way.

The fact that the original fate spider gives up, quits his job and then only comes back after his successor has screwed everything up even more says a lot, at this point they seem to pretty much just watch and be amazed that all of creation hasn't gone up in flames already.

In a later strip, Old-Riff says that Time Travel follows the branching timeline rules, and therefore you can't change the past, you're just abandoning the Bad Future in favor of a different universe. But really, the way it works, this revelation doesn't actually contradict anything, since from the characters' perspective, they would have no way of knowing.

The robot Gizmo goes back in time to kill Hitler, reasoning that he can then go back again and stop himself. Instead, his first iteration convinces him to join in, since he can just go back again, and stop himself. Predictably, they end up having dozens of Gizmos brutalizing Hitler before he's had enough and stops his first self... and gives him a video recording of the event.

In another chapter, Gizmo went insane from a virus while saving the ship. The other crew members fix this by taking his head off (it contains his processors and memory drives), going back in time to just before he went insane, and switching heads, thus bringing his sane head back to the present while the insane one faces the virus (presumably, he can't go even insaner).

Imagine four balls on the edge of a cliff. Say a direct copy of the ball nearest the cliff is sent to the back of the line of balls and takes the place of the first ball. The formerly first ball becomes the second, the second becomes the third, and the fourth falls off the cliff. Time works the same way.

Awful Hospital: The alien zones don't always use "time" as we humans understand it, but something called "layers." Chronology can sometimes jump around on its own, via layers, without Fern needing to enter a time machine:

Staph: As you read this letter, our kingdom will have undergone many generations of development... at least from our perception. Don't fret! In your own perception sphere, we are very much alive, and I'm certain you will have an opportunity to drop in and say 'hello.' Does that make sense? Sorry, we still don't really have a handle on how you experience the layers.

Mind My Gap is a plot made of this. It seem at one point that up to four chronologically separate events with the same characters involved are happening at exactly the same time

Phaeton has time travel mechanics, but also has laws, and etiquette, all to prevent this from happening. Still there are people who don't follow the "Six Minute Flux" mechanic and cause this.

According to Huey in Ducktalez 5, the time-travelling Deweys all come from alternate timelines that are created when one of them tries to change history. Huey offers a situation, but that fails. Also, Dewey tries to ask for the Doctor's help, but that fails.

In the Adventures of Sonic the Hedgehog multi-parter Scratch and Grounder made it so a couple of Sonic's ancestors didn't meet, making Sonic disappear. But for some reason Tails is still there and able to fix this.

In the double-episode "Two Futures" of Captain Planet and the Planeteers, Wheeler uses a time pool to go back and prevent himself from receiving the fire ring. This results in a crapsack future because the Planeteers never became a team and saved the environment (though why they didn't just find another guy to accept it is never explained). He then goes back and prevents himself from preventing himself from getting the ring. Then they both escape into the time pool again and merge for some reason. To make sure the viewers knew things were restored to normal, a scene from the utopian future is shown at the very end.

Time travel in The Fairly OddParents! is... confusing. The first time Time Travel is used as a plot device, and in most subsequent appearances, history is very malleable and can easily be changed... with serious consequences.

However, the episode "The Secret Origin of Denzel Crocker" appears to utilize a straight Stable Time Loop... however Timmy's time traveling, in addition to causing Crocker to lose his fairies as a kid, also gave him a much more sophisticated fairy-tracker which he didn't originally have as an adult, meaning that Crocker must have lost his fairies a slightly different way the "first time around".

In a much later episode when Timmy wishes he were never born, a laIt's a Wonderful Life, Jorgen reveals that Crocker's childhood would never have been ruined had Timmy never existed, which means that there was no "first time around" note if there were, one would expect that Timmy negating his own existence would have undone all his changes to the past and history would be restored to the way it originally proceeded, sans Timmy of course. In other words, the writers wanted to use both Stable Time Loops and Temporal Paradoxes at the same time, resulting in a confusing mess. Cosmo did a lot to get little Crocker obsessed with fairies, but he only got the opportunity due to Timmy.

Time travel results in the creation of Stable Time Loops... except when it doesn't. In "Roswell That Ends Well", You Already Changed the Past is in effect, and everything makes sense. Then "The Why of Fry" contradicts this, and Fry succeeds in altering his own past (he doesn't prevent himself from getting cryogenically frozen, as he originally intended, but he does convince the Nibblonians to give him a better getaway scooter). Then, Bender's Big Score throws sense out the window: Bender's rampant time travel is revealed as the cause of some events from previous episodes (such as the fossilization of Seymour, and the first destruction of Old New York by flying saucers), while completely altering some other events (the final scene of "Jurassic Bark" gets retconned). Both stable time loops (like the tattoo on Fry's butt) and utter nonsense (like Hermes Conrad stealing his own body from the past) work equally well. Rather appropriately, Bender's time travel is carried out by a literal Timey-Wimey Ball.

The entire existence of Lars Fillmore is built on a combination of a Stable Time Loop and an Alternate Timeline. In the future, Fry meets Lars before going back to his own time. He then takes another trip back in time by an hour, displacing the Fry that existed at that time and turning him into a "time-paradox duplicate." The duplicate eventually becomes Lars, following his other self to the future and inspiring the original Fry to take on the false identity of Lars once he becomes a duplicate though his upcoming use of time travel.

Then there's Professor Farnsworth's time machine in "The Late Philip J. Fry", which could only go forward in time. When Farnsworth, Fry and Bender returned to a new, identical universe (making the Big Bounce theory true) It's impossible to know if the killing of the fish or Hitler did anything to Universe Two because they didn't get to stop in the 31st century to find out. They had to go around again to finally make a stop at Universe 3. This leads to all sorts of crazy implications as to what happened to the time traveling crew in the 2nd universe...do they kill their Universe 4 selves?

On the DVD commentary for "Roswell," the writers say that they initially intended to avoid doing any time travel stories, because it's basically impossible to make them make sense, but eventually they couldn't resist.

The Penguins of Madagascar has Kowalski try to stop two paradoxes that he created at the same time. While it's eventually resolved with a stable time loop, the second/third Kowalski couldn't have existed without having it's own paradox. It's... confusing. And the paradoxes effect time is only a few hours.

The plot of a Pinky and the Brain episode, in which the mice try to obtain a "World Domination Kit" from the future. It doesn't even try to make sense, but suffice to say it ended with the lab full of hundreds of Pinkys and Brains, and the ending tune changed to "They're Pinkys, they're Pinkys and the Brain Brain Brain Brain Brain Brain Brain Brain Brain Brain."

Randy Cunningham: 9th Grade Ninja: When the past was altered so the Sorcerer's imprisonment never happened, it got the Sorcerer free but didn't change the world in any way that reflected the damages he would have caused during eight centuries of altered history. No explanations were given.

Sealab 2021: "Lost In Time" shows Stormy and Quinn trying to steal cable for Captain Murphy and inadvertently cause a rift that sends them back in time to just before they left Sealab (about 15 minutes). They try to prevent themselves from causing the rift, but past Captain Murphy is convinced they are evil dopplegangers and not time travelers, so he has them locked in the brig. When their past-selves cause the rift (again), they experience the same events but somehow the original pair is also in the brig when they get there. So now there's 3 Stormies and 3 Quinns running around. Since the time difference is only 15 minutes, each successive Stormy and Quinn react in the same way, and since each pair is unable to stop the next pair, the number of Stormies and Quinns keeps growing until the brig is filled with them and they have to start referring to each other by which iteration of the loop they came from (i.e. Quinn 1, Quin 2, "the 7s", etc). Eventually time itself is getting so screwed up that weird alternate versions of them start showing up too (like pixie versions, or Quinn as Jabba the Hutt and Stormy as Salacious Crumb). The Quinns band together to try and think of a solution, while the Stormies play dodgeball. Ultimately, one of the Stormies reveals that they've been using their communicator watch(es) the whole time (but only with already locked up Stormies). One of the Quinns borrows it to call the version who is out stealing cable and finally ends the loop by averting the next explosion. Then, instead of using the combined brain power of dozens of genius Quinns to solve major world problems, Captain Murphy has all the duplicates fight to the death in the gym for his amusement.

Sonic SatAM screws up it's time travel rules quite confusingly. Sonic and Sally try to travel back in time to before Robotnik's coup in order to stop him, but soon discover that this is impossible and they can't change the past, merely act out or ensure predetermined events (Sonic causes Robotnik's arm to be robotized, saves his younger self from getting captured, etc.). However at the last moment Sally attempts to change the fate of her nanny by telling her future information and it works, even though it logically shouldn't have. Even more confusingly, Ripple Effect-Proof Memory is in effect, so Sonic and Sally don't remember interacting with someone they now logically should. Sonic is appropriately confused.

In one episode, Cartman freezes himself and is thawed out 500 years in the future. He then makes repeated calls to Kyle via a phone that reaches back through time, which makes changes to his time. He and everyone else 500 years from now only know the world the way it is after the changes. However, when he makes one more change at the end that hugely impacts history, he only remembers what the world was like before the change, while from everyone else's point of view it's always been that way.

In the episode "Goobacks" immigrants from the future come back through a time portal to get jobs in the present. When the townspeople try to improve the future so the immigrants will stay in their time period, the immigrants begin to fade away. A reporter notes that scientists say the time border follows Terminator rules meaning it's one way only and you can't go back as opposed to Back to the Future rules, where back and forth is possible, and Timerider rules, which are just plain silly.

After Thrust shoots Starscream with the Requiem Blaster, we see a shot of Rad as an eight year old waking up in his parents' car and asking tiredly where the Mini-Cons are (implying his "present" mind was momentarily in his past body). Then cut to all the kids - possibly in an alternate future - being told by a slowly dying Hot Shot that the Transformers have all been eaten by Unicron because they didn't know that the Mini-Cons were servants of Unicron and were led to their doom. After this, cut to the kids now being at the moment of the Mini-Cons' creation millions of years ago inside Unicron. Rad then touches High Wire's hand and frees him (and by association all the other Mini-Cons) from Unicron's control by reminding them of their past/future happiness together. The Mini-Cons then know to go to Earth after they leave Cybertron to meet Rad and the other humans. Cut back to the humans returning mere moments before Thrust shoots Starscream, whereupon High Wire and his teammates combine into Perceptor and knocks the gun away, causing Thrust to miss Starscream completely. And none of this is EVER EXPLAINED.

The Mini-cons who prevented Starscream from being blastedweren't taken along with the kids' inexplicable time-jump, and there is no reason for them to have done anything differently in the present. It can't even be due to the kids' actions in the past — the Mini-cons would never have gone to Earth to kick off the events of the series if not for the kids, so it's not a case of the "old" High Wire wanting Starscream to die but the "new" one saving him.

There's a gigantic lampshade in Tripping the Rift. The crew saves the day by turning back time Superham-style: by flying the ship around a star counterclockwise really fast. While they're setting up, they discuss the inconsistency of the rules of time travel and the problems with changing the past.

In X-Men, Bishop keeps his memories of the previous chain of events when he returns into the future. Later the two parter "One Man's Worth" has the death of Charles Xavier before he founded X-Men resulting into a war-torn present. Wolverine and Storm from this changed reality travel into the past to help to save him. After the successful mission accomplishment they return into the future (present time) and for some reason lose all their memories about the Xavier-less reality.

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